Vinokourov won Stage 13, which was an individual time trial, last Saturday, and Monday's Stage 15. He started the 2007 Tour de France as a favorite but a fall the first week put him behind. He is in 23rd place overall, more than 28 minutes behind leader Michael Rasmussen.
On the Tour de France Web site, officials said: "Doping ruins our childhood dreams. Vinokourov has cheated and the only possible answer was: Leave!"
Tour officials said the manager of the Astana team, Marc Biver, that Vinokourov tested positive on Saturday. Astana said it was withdrawing from the competition. That means that Astana team member Andreas Kloden, in fifth place overall, is also out of the Tour de France.
Tuesday marked the final off day of the more-than 2,200-mile Tour de France. Racing is to resume Wednesday with a 136.5-mile ride from Orthez to Gourette-Col d'Aubisque. The 2007 tour is scheduled to wind up Sunday in Paris.