Landis is suspended from racing until January 2009
Floyd Landis has failed in his bid to overturn his two-year doping ban at the Court of Arbitration for Sport.
The American had hoped to have his 2006 Tour de France win restored after he was stripped of it for testing positive for elevated levels of testosterone.
The 32-year-old appealed to the Court after a US arbitration panel upheld laboratory findings that he used synthetic testosterone.
Oscar Pereiro was declared Tour winner following Landis's positive test.
Landis leapt back into contention in the 2006 Tour after producing an astonishing comeback on the final mountain stage, just a day after a poor performance had appeared to end his hopes of victory.
Testosterone can speed up recovery after exercise and improves stamina and strength.
He maintained his innocence during his US arbitration hearing, which was open to the public, blaming mistakes in the testing procedure by the French laboratory for the result.
But in its ruling, the court said the laboratory "did not violate the International Standard for Laboratories".
It concluded that "the presence of exogenous tesosterone or its precursors of metabolites in Floyd Landis' sample proves that he violated the anti-doping rules of the International Cycling Union".
I am looking into my legal options and deciding on the best way to proceed
Landis is the first rider in Tour history to be stripped of the title for a doping offence.
As well as failing to overturn his ban, he has been ordered to pay around £50,000 in costs to the US Anti-Doping Agency for its involvement in the case.
"We are pleased that justice was served and that Mr. Landis was not able to escape the consequences of his doping or his effort to attack those who protect the rights of clean athletes," said USADA chief executive officer Travis Tygart.
Landis said he was "saddened" by the verdict.
"I am looking into my legal options and deciding on the best way to proceed," he added.