Olympic and World Championships marathon gold medallist Peres Jepchirchir has been provisionally suspended by the Athletics Integrity Unit after an out-of-competition sample tested positive for EPO.
Kenyan Jepchirchir provided the sample prior to winning the Sydney Marathon on 30 August 2026.
The 33-year-old clocked a time of two hours, 18 minutes and 31 seconds to win in Sydney.
EPO, or erythropoietin, is a natural substance produced within the kidneys that stimulates the creation of new red blood cells.
If injected, it is only detectable in the urine or blood for a short window of time, and increases the amount of red blood cells, which carry oxygen to the muscles, in the blood stream.
Jepchirchir became the Olympic women's marathon champion at the 2020 Tokyo Olympics and returned to the Japanese capital to win the World Championships in September 2025.
She broke the women's half-marathon world record in 2017 and on three occasions in 2020.
In addition to Sydney, her other major wins came at the New York Marathon in 2021, the Boston Marathon in 2022 and the London Marathon in 2024.
Jepchirchir won the Sydney race, which became the seventh world major in 2025, by more than three minutes from compatriot Irene Chepet Cheptai.
She provided the sample which tested positive for EPO while in Kenya prior to the race.