Pancrase Marquardt began his professional mixed martial arts career in 1999, and amassing victories in various promotions before entering the
Bas Rutten Invitational 4 tournament, which was organized in such a manner that the tournament winner was to be offered a contract with the
Ultimate Fighting Championship. Despite winning the tournament, Marquardt was offered no such contract. Instead, he signed with Japan's
Pancrase organization, which had fostered such fighters as
Ken Shamrock and
Bas Rutten. In his first Pancrase fight, Marquardt lost via
submission to
Genki Sudo. Invited back to Pancrase for a
middleweight elimination tournament, Marquardt defeated
Daiju Takase,
Kiuma Kunioku, and
Shonie Carter to become the first middleweight King of Pancrase. Marquardt defended this title twice before being defeated by Kunioku in December 2001. A final encounter between the two fighters in December 2002 saw Marquardt defeat Kunioku once again to recapture the
King of Pancrase championship, which he held for nearly a year. On November 30, 2003, Marquardt was involved in a brief altercation with
Ricardo Almeida in a Pancrase title fight. Marquardt tapped out to a
guillotine choke, however, the referee was unable to immediately separate the fighters, and Almeida continued to apply the choke, posing for ringside cameras. After he was freed, Marquardt threw a strike at Almeida's face, prompting both corners to storm into the ring, including
Renzo Gracie. Renzo was cornering Almeida, and once in the ring he kicked Marquardt in the face. The confrontation eventually came to an end, and Marquardt approached Almeida after the bout to congratulate him. After Almeida vacated his title in July 2004, Marquardt proceeded to regain the championship in a victory over
Kazuo Misaki at
Pancrase: Brave 10. On May 1, 2005, Marquardt defeated
Izuru Takeuchi, winning the
Pancrase Middleweight Championship for the seventh time, becoming the only fighter to ever accomplish such a feat.
Ultimate Fighting Championship Marquardt made his
UFC debut on August 6, 2005, live on
Spike TV, headlining the inaugural
UFC Ultimate Fight Night card in Las Vegas, Nevada. Although Marquardt earned a unanimous decision victory over UFC veteran
Ivan Salaverry, a post-fight drug test revealed high levels of
nandrolone, an
anabolic steroid, in Marquardt's system which led to the
Nevada State Athletic Commission filing for his suspension. Marquardt maintains that he only used over-the-counter supplements in preparation for the fight. Marquardt was initially suspended for six months and assessed no fine. Marquardt's suspension was reduced to five months and he was reinstated in January 2006. With the drug testing controversy resolved, Marquardt was set to make his return at
UFC 58, against veteran
Joe Doerksen. The fight proved to be a successful endeavor for Marquardt, as he won a unanimous decision. In the post-fight interview, Marquardt stated his goals of capturing the
UFC Middleweight Championship and his intention to fight then-champion
Rich Franklin. Marquardt then fought Crafton Wallace, a replacement for Marquardt's original opponent,
Thales Leites, on the undercard of
Ortiz vs. Shamrock 3: The Final Chapter on October 10, 2006. Marquardt won by
rear-naked choke in the second round. Due to his commitment to the UFC, Marquardt relinquished his title as the
Pancrase Middleweight Championship that same month. At
UFC Fight Night 8, Marquardt notched a dominant unanimous three-round decision victory over
ADCC Champion grappler
Dean Lister that saw two judges score the bout 30-25 for Marquardt.
Middleweight title shot Following that victory and a 4-0 debut in the UFC, Marquardt was scheduled to compete for the
UFC Middleweight Championship held by
Anderson Silva on July 7, 2007 at
UFC 73. Marquardt lost the championship bout by TKO due to strikes at 4:50 in the first round of the fight.
Road back to title contention After early speculation that Marquardt's contract with the UFC could expire without renewal, he confirmed that a new agreement had been signed with the organization. Marquardt's next match was to be against
Thales Leites at
UFC 81, but Leites withdrew from the bout due to an injured hand. This marked the second time that a bout between Leites and Marquardt had been cancelled. On January 9, the UFC announced that veteran
Jeremy Horn would be Leites' replacement. Marquardt defeated Horn via
guillotine choke in the second round. Marquardt finally fought Thales Leites at
UFC 85, a fight that had been postponed on two separate occasions since 2006. Marquardt was winning the fight very dominantly, but landed an illegal knee strike to the head of Leites in the second round costing him a point. In the third round Marquardt landed an elbow to the side of the head of Leites, costing him a second point. Referee Herb dean thought it was an illegal strike, and deducted a second point. The strike was to the side of the head and clearly legal in the replay. However, the deducted points proved to be crucial as Leites was deemed victorious in a very close split decision, giving Leites a title shot against Anderson Silva. Marquardt was next scheduled to face
Martin Kampmann at
UFC 88. Nate defeated Kampmann in 82 seconds by throwing a head kick and landing a barrage of strikes to take the win by TKO in the first round. Marquardt obtained a second straight win to launch himself back into the title picture at
UFC 95, when he defeated well-regarded Brazilian fighter
Wilson Gouveia with another barrage of strikes to earn a third-round TKO. Marquardt's next fight was against the then-undefeated submission specialist
Demian Maia at
UFC 102, which he won via KO 21 seconds into the first round by landing a counter straight right as Maia threw a leaping leg kick. Maia fell face down, unable to protect himself. Nate rushed in to follow up with a right hook, but stopped himself once he saw that Maia was visibly hurt. This fight earned him a $60,000
Knockout of the Night award. Following his victory over Maia, Marquardt was scheduled to fight
Dan Henderson to determine number one contendership to Silva's Middleweight Championship. Henderson left the UFC for
Strikeforce after attempts to agree on a new contract failed. A new bout was arranged between Marquardt and American wrestler
Chael Sonnen, scheduled for
UFC 110 and later moved to
UFC 109. Marquardt was taken down at will by Sonnen multiple times during each round. Although able to lock in a guillotine choke late in the third round, Marquardt was not able to finish the submission attempt and lost the fight in an upset via unanimous decision. This fight earned him a $60,000
Fight of the Night award. Marquardt was expected to face
Alessio Sakara on July 3, 2010 at
UFC 116 but the fight was cancelled after Sakara pulled out due to the death of his father. Marquardt was expected to face
Rousimar Palhares on August 28, 2010 at
UFC 118, however the bout was moved to September 15, 2010 to headline
UFC Fight Night 22 after
Alan Belcher was forced to pull out of his bout with
Demian Maia with an eye injury. Marquardt defeated Palhares via first-round TKO. During the fight, Palhares went for a heel-hook from which Marquardt slipped his leg free and Palhares looked at the referee and pointed to Marquardt's legs, seemingly complaining that Marquardt was greased. Marquardt capitalized on the opening and pounded Palhares with a quick barrage of punches to get the stoppage. The ending, though, was not due to any illegal circumstances. UFC broadcaster
Joe Rogan immediately announced that Marquardt had passed an inspection from the ringside physician and the referee. Marquardt explained that before the fight; "I came out really warm because I wanted a good sweat," which explains why he was slippery and managed to remain elusive. Less than a week after his win over Palhares, Marquardt was tapped to make a quick return to the Octagon to face
Yushin Okami in a middleweight title eliminator bout on November 13, 2010 at
UFC 122, replacing
Vitor Belfort, as Vitor was promoted to a title fight because of
Chael Sonnen's suspension for PEDs. Marquardt lost to Okami via unanimous decision. Marquardt was expected to face
Yoshihiro Akiyama on March 19, 2011 at
UFC 128. However, Akiyama pulled out of the bout and was replaced by
Dan Miller. Marquardt won the fight via unanimous decision.
Drop to welterweight and release from UFC After defeating Miller, Nate's teammate,
Georges St-Pierre, gave him the idea of dropping down to the
welterweight division. Marquardt was expected to debut at welterweight against
Anthony Johnson on June 26, 2011 at
UFC on Versus 4. However, Johnson was forced out of the bout with a shoulder injury and replaced by
Rick Story. Marquardt pulled out of the fight with Story the day of the weigh-ins due to not receiving medical clearance. The UFC at the UFC on Versus 4 weigh-in announced that Marquardt did not pass the required physical. According to a video posted by
Dana White on his
Twitter, Marquardt was released by the UFC due to failing "medical requirements". On June 28, 2011, Nate appeared on MMA Hour with
Ariel Helwani and stated that in August 2010 he felt tired and moody and his doctor discovered he had low testosterone levels. That doctor put Nate on hormone replacement therapy, and when Nate applied for a Therapeutic Use Exemption with the New Jersey state commission, they allowed it but declared that he must go off the therapy for ten weeks, then have his levels retested by a specialist to determine if he really needs to be on the therapy or not. At the end of that period, both the specialist and Nate's primary doctor agreed his levels really were low and he was a candidate for replacement therapy. Nate's primary doctor injected him with testosterone to quickly get his levels back up in time for his scheduled fight against Story. The Pennsylvania commission had set standards for what his testosterone levels could be at fight time and Nate's levels, though trending down over the last week before the fight, still failed to fall to within the range required in time for him to be cleared to fight. Nate claimed that he retook tests on the day of the fight and was actually within qualifying limits, thus having his suspension lifted by the commission.
BAMMA Shortly after having his suspension lifted by the Pennsylvania State Athletic Commission, Marquardt signed with top U.K. fight promotion
BAMMA, the British Association of Mixed Martial Arts. He told MMAWeekly.com that a large part of the reason for signing with BAMMA was that even though the U.K. does not conduct governmental sanctioning of MMA, BAMMA officials were moving ahead with their own plans to self-regulate, including medical screening and drug testing. He was set to make his promotional debut at
BAMMA 9: Marquardt vs Yoshida on February 11, 2012 against
Yoshiyuki Yoshida to determine the inaugural
BAMMA World Welterweight Champion. On January 13, 2012, Marquardt was released from his contract with BAMMA officially due to the promotion pushing back BAMMA 9, and therefore his promotional debut, to March 24, 2012.
Strikeforce Dana White announced that Marquardt had signed with
Strikeforce. His debut took place at
Strikeforce: Rockhold vs. Kennedy against
Tyron Woodley in a bout for the vacant
Strikeforce Welterweight Championship. Nate knocked out Woodley in the fourth round, becoming the new
Strikeforce Welterweight Champion. Marquardt's first defense was against
Tarec Saffiedine on January 12, 2013 at
Strikeforce: Marquardt vs. Saffiedine. He lost the belt via unanimous decision.
Return to UFC and retirement Marquardt faced
Jake Ellenberger on March 16, 2013 at
UFC 158. He lost the bout via first-round KO. Marquardt faced
Héctor Lombard on October 19, 2013 at
UFC 166. He lost the fight via knockout in the first round. Marquardt made a return to the middleweight division to face
James Te-Huna on June 28, 2014 at
UFC Fight Night 43. He won the fight via first round submission due to straight armbar. This fight earned him a
Performance of the Night award. Marquardt faced
Brad Tavares on January 3, 2015 at
UFC 182. He lost the fight by unanimous decision. Marquardt faced
Kelvin Gastelum on June 13, 2015 at
UFC 188. He lost the fight via TKO after his corner stopped the fight between the second and third round. Marquardt faced
C. B. Dollaway on December 19, 2015 at
UFC on Fox 17. He won the fight via knockout in the second round. Marquardt next faced
Thiago Santos on May 14, 2016 at
UFC 198. He lost the fight via knockout in the first round. Marquardt next faced
Tamdan McCrory on October 1, 2016 at
UFC Fight Night 96. Marquardt won the fight via knockout in the second round and was awarded a
Performance of the Night bonus. Marquardt faced
Sam Alvey on January 28, 2017 at
UFC on Fox 23. He lost the fight via unanimous decision. Marquardt faced
Vitor Belfort on June 3, 2017 at
UFC 212. He lost the fight via unanimous decision. Most pundits had Marquardt winning the fight. Marquardt faced
Cezar Ferreira on November 11, 2017 at
UFC Fight Night 120. He lost the fight via split decision. On December 28, 2017, Marquardt announced his retirement from professional MMA fighting after 56 fights over an 18-year MMA career.
Return to competition Marquardt came out of retirement for the first time in nearly four years to face Michael Cora on August 6, 2021 at Titan FC 71. He won the bout via armbar submission in the first round. He next faced Valdir Araujo at XMMA 3 on October 23, 2021. Marquardt lost the bout via TKO after suffering a body kick and punches. ==Personal life==