The first doping case became known at the Olympic Winter Games in Beijing.
Iranian alpine skier Hossein Saveh Shemshaki has tested positive in a doping control.
As the International Test Agency (Ita) announced on Thursday night, he was checked outside of the competition on Monday.
The athlete was informed of the case and suspended until clarification.
Shemshaki will not be allowed to participate in any competitions, training, mentoring or other activities during the Winter Games, the statement said.
The 36-year-old was in Vancouver in 2010 and in Sochi in 2014 – in Russia he achieved his best result with 31st place in the slalom.
According to Ita, the athlete has the right to challenge the imposition of the provisional ban before the Arbitral Tribunal of the International Court of Arbitration for Sports and to request an analysis of the B sample.