Club: AFC Ajax
Growth Type: Standard/Lasting
De Boer began his career as a left back at Ajax before switching to centre back, a position he made his own for many years in the national team. He won both the UEFA Cup and Champions League while at Ajax. However, after signing a 6-year contract extension with Ajax for the 1998–99 season, he and his twin brother Ronald took successful legal action to have it voided. Ajax had agreed orally that if a lucrative offer for one brother came by, he would be released provided the other stayed. However Ajax apparently backed down on that agreement after floating the club on the stock market and pledging to shareholders that it would hold both of the de Boers and build around them a team to recapture the UEFA Champions League.
Both de Boers then joined FC Barcelona for 22 million pounds. However, they were unable to repeat his earlier triumphs and Frank suffered the ignominy of testing positive for the banned substance nandrolone. De Boer was suspended but he was reinstated after a successful appeal
He briefly moved to Galatasaray in the summer of 2003 before joining Rangers in January 2004. He left Rangers in 2004 after Euro 2004 along with twin brother Ronald (his teammate at Ajax, Barcelona and Rangers) to play the rest of his football career in Qatar with Al-Rayyan.
De Boer announced his retirement from football in April 2006.