Yulia Efimova without a pool.

Yuliya Andreyevna Yefimova, also romanized Efimova, (born 3 April 1992) is a Russian competitive swimmer. Yefimova competed for Russia at the 2008 Beijing Olympics, the 2012 London Olympics, and the 2016 Rio Olympics. In London she won the bronze medal in the 200 metres breaststroke and in Rio de Janeiro she won a silver in the 100 metres breaststroke.

Yefimova broke the long course 50 m breaststroke world record at the Barcelona 2013 FINA World Championships, as well as winning the gold medal in the 50 m and 200 m breaststroke races at the same Championships. She held the world records in short course 50 m and 200 m breaststroke. In 2014, she failed a drug test and was suspended from competition for over a year.

Yefimova's first notable achievements were winning thrice at the Short Course Swimming Championships in 50 m, 100 m and 200 m breaststroke. At the 2008 European Aquatics Championships she was the gold medalist in 200 m breaststroke and silver medalist in 50 m. She participated at the 2008 Summer Olympics in Beijing, reaching fourth place in 100 m and fifth place in 200 m breaststroke. That year, the National Swimming Federation named her "Breakthrough of the Year".

In 2010, Yefimova won gold medals at the 2010 European Aquatics Championships in 50 m and 100 m breaststroke. In 2012, Yefimova received bronze in 200 m at the 2012 Summer Olympics, with a national record of 2:20.92. A year later at the 2013 World Aquatics Championships in Barcelona she triumphed in 200 m, beating Rikke Pedersen and Micah Lawrence and updating the national record to 2:19.41. In the 50 m heats event, the Russian achieved a new world record of 29.78 which was broken in the semifinals by Rūta Meilutytė. Yefimova won the finals with 29.52, the new national record.

After five months of disqualification after a positive drug test, Yefimova in August 2015 for the first time won the gold medal in 100 m at the World Aquatics Championships, with 1:05.66. In 50 m she was third with 30.13. However, in 200 m she was eliminated in the semifinals; she was 17th. At the National Championships, Yefimova won two medals, including one gold medal.

In June 2016, Yefimova returned at the Los Angeles Invitational, winning in 200 m with 2:22.77. Notwithstanding the cold atmosphere within the audience with persistent boos towards her, Yefimova became silver medalist at the 2016 Summer Olympics in 100 m.

Doping scandals
In 2014, Yefimova failed a drug test. Her positive test was for DHEA, an endogenous steroid hormone banned in professional sports. On May 13, 2014, she was disqualified from October 31, 2013, until February 28, 2015. She was also stripped of her results and medals at the 2013 European Short Course Championships. Her world records were also invalidated. Yefimova also tested positive for meldonium in March 2016. She was provisionally banned by the International Swimming Federation (FINA). This suspension was later put on hold while the World Anti-Doping Agency investigates the drug.