Dimitry Fofonov has been fired by the Credit Agricole team after testing positive for heptaminol during the Tour de France.
The Kazakh rider produced a positive A sample following the 18th stage from Bourg d'Oisans to St Etienne, which was won by Marcus Burghardt.
Fofonov's failed test was confirmed by race organisers shortly after Carlos Sastre claimed overall victory after Sunday's final stage into Paris.
Credit Agricole, the French bank which sponsors Fofonov's former team, had announced prior to the Tour that they were ending their sponsorship at the end of 2008.
The team won two stages of the Tour through Thor Hushovd and Simon Gerrans.
Fofonov is the fourth rider to test positive for a banned substance on the 2008 Tour after Manuel Beltran, Moises Duenas Nevado and Riccardo Ricco, who all were found guilty of EPO use.