Alex Schwazer, the 2008 Olympic race walk gold medal winner, has been banned for eight years after his appeal against a provisional doping suspension was rejected by the Court of Arbitration for Sport (CAS).
The IAAF imposed a provisional ban on Schwazer, who won gold in the 50km race walk at the Beijing Games, following a positive test for a steroid in May.
Schwazer, who previously served a three-and-a-half-year doping suspension that forced him to miss London 2012, requested his appeal be treated as urgent ahead of the Rio Games.
But, after CAS oversaw an expedited procedure, the adjudication body ruled the 31-year-old will not be able to compete in Brazil and hit him with a lengthy ban.
A CAS statement read: "The Court of Arbitration for Sport (CAS) has dismissed the appeal filed by the Italian race walker Alex Schwazer who challenged the provisional suspension imposed on him by the International Association of Athletics Federations (IAAF).
"Furthermore, the CAS sanctioned him with an eight-year period of ineligibility starting on the date of today, less any period of provisional suspension effectively served as of 8 July 2016.
"All competitive results obtained by Alex Schwazer from and including 1 January 2016 are disqualified with all resulting consequences, including forfeiture of medals, points and prizes."