Early history (1871–1967) The parent organisation,
Associazione Ginnastica Senese "Mens Sana in Corpore Sano 1871", was formed on 16 April 1871 by university students. In the beginning of the 19th century the gymnastics club became a multi-sports club () by adding other sports under its wing. Basketball was first practiced by the club in May 1907 at the Venice Gymnastics competition when teacher Ida Nomi Pesciolini led a women's team in a basketball demonstration. It is claimed this was the first time the game (invented in 1891) was played in Italy, with Nomi discovering the sport whilst in the United Kingdom and then translating the rules in Italian. The official basketball section of the club was established in 1934; however, the club and the organisation as a whole had limited activities until the end of the Second World War in 1945. After that date, basketball was played again, at first by students from the Piccolomini high school. In 1978–79, Antonini Siena reached the Serie A quarterfinals, earning a place in the
1979–80 FIBA Korać Cup where they went to the Round of 16. Only two seasons later the side was in the second division again and at the end of the 1986 season it moved down to the third division Serie B Eccellenza. Siena would stay there until 1990, returning to the Serie A in 1991 and staying there for good from 1994. At the beginning of the decade, the club had become autonomous from the Polisportiva. With the return of Thornton and the addition of
Kšyštof Lavrinovič, Montepaschi reached the
2008 Euroleague Final Four after sweeping their quarterfinals. A 17-point second-half lead against
Maccabi Tel Aviv proved insufficient as the Italians lost in the semifinal. On the domestic front, Siena started
the season with 18 successive wins and were never challenged in their third title conquest. In
2008–09, Siena became the second side to complete a domestic treble after losing just one game on their way to the league,
Cup and Supercup titles. After adding
Nikos Zisis,
Marko Jarić,
Malik Hairston and
Bo McCalebb, Montepaschi reached another
Euroleague Final Four in 2011, overcoming then-top scorer McCalebb's injury and a record 48-point loss to
Olympiacos in the quarterfinals game 1; however, they were again stopped in the semifinals, this time by champions
Panathinaikos. In
the league they proved unstoppable again, adding a fifth straight Serie A crown and a third straight Cup title to their trophy cabinet. In
2011–12, Montepaschi achieved an unprecedented sixth consecutive Serie A title, adding the Supercup (their fifth in a row) and Cup (fourth) for good measure. The
2011–12 Euroleague saw eventual champions Olympiacos avenge their preceding year's defeat by topping the Italians in the quarterfinals. All the titles won during this season were to be revoked four years later by the Italian Basketball Federation, following an investigation for accounting and fiscal fraud.
2012–13 saw two major changes with a decrease in budget that saw several players leave and a change in coach, with Pianigiani replaced by assistant
Luca Banchi. Montepaschi wasn't as competitive, being eliminated at the
Euroleague Top 16 stage whilst in the domestic league they finished the regular season in fifth place with 12 losses; however, the holders rallied in the playoffs, winning two Best-of–7 series in game 7, against
EA7 Emporio Armani Milano and
Cimberio Varese before toppling
Acea Roma 4–1 in the finals to add title number seven to the Cup they had earlier won. This title too was revoked three years later by the Italian Basketball Federation. The next season (2013–2014) saw an ever-contracting budget and a more ordinary roster, Montepaschi found it harder to compete in the
2013–14 Euroleague, alternating between close wins (sometimes on the buzzer) and closer defeats, ending the season with 3 wins and 7 losses. In their final game against
Unicaja that would decide who progressed from the group, the Italians were the victims of a buzzer beating shot that eliminated them from the competition. Though its financial problems emerged to the fore, with a relegation all but assured due to massive debts, on the court the holders kept fighting, pushing favourites Milan to seven games in the
Serie A finals, though they would go on to concede the title. Soon after, Mens Sana Basket was declared bankrupt amidst debts of 5,4 million euros and the departure of sponsor Montepaschi even if the company had revenue for over 400 million Euro. Furthermore, an inquest had been started in 2012 after suspected undeclared payments and tax evasion by club officials for over 90 million Euro, including former president Ferdinando Minucci. On 25 October 2017, following an investigation for accounting and fiscal fraud, including the destruction of some of the company's accounts by the president Ferdinando Minucci, the
Italian Basketball Federation revoked all the domestic titles won by the club during the 2011–12 and 2012–13 seasons, namely two Italian titles, two Italian Cups and an Italian Supercup. In March 2019, Siena was excluded from the West Group of the Serie A2 for economic issues. In the beginnings of 2019, the team's roster was practically dismantled due to the club's financial troubles making it impossible to pay the league's taxes and the wages. The exclusion was determined after various renounciatiouns by the team to play certain games and on the charges of "unsportsmanlike conduct", since its line-up altered the competitiveness of the league. Following the exclusion, the team was renamed as Mens Sana Siena Basketball Academy, after absorbing again the control of Mens Sana's former satellite youth team; and enrolled for the 2019–20 Promozione Toscana, in the 7th tier of the
Italian Basketball Federation. Such league was suspended due to the
COVID-19 pandemic in Italy with Siena in the lead. On 21 August 2020, it was announced that Mens Sana Siena would be participating on the Group A of the Serie C silver, a regional league representing the 5th Tier of the
Italian Basketball Federation. ==Arena==