When he was not drafted in the
1964 NBA draft, Aiken went to Europe to play basketball. He used a brace on his injured knee. He also played for the Newcastle Eagles in 1965–66 under Spanish coach
Antonio Diaz Miguel, and led the National League in scoring with 23.9 points per game. In 1967, he led his team with 31 points in its semifinal win over Olimpija, 88–86, and he had 23 points in the
EuroLeague Final to help Real Madrid beat
Simmenthal Milano. In 1968, in the title game he
led all scorers with 26 points to lead Real Madrid to the title against
Spartak Brno, 98–95. In the 1969 European Cup final CSKA Moscow beat Real Madrid in double overtime, as he led Madrid with 24 points. He joined
Partenope Napoli that summer and led it to the 1970
Saporta Cup title, over
JDA Dijon Basket.
Jet magazine noted that he was one of four blacks in the European finals, along with Rudy Bennett (New York University), Larry Robertson (Oklahoma University), and Jim Williams (Temple University). Concurrently with playing for the team, he coached, and earned a long-distance teaching degree at the
University of Southern California. He worked in England as a teacher after completing his studies. On February 3, 2008, Aiken was among 105 players nominated for the
50 Greatest EuroLeague Contributors list. ==Career after basketball==