Janeth Jepkosgei Busienei (born 13 December 1983) is a Kenyan middle distance runner and former world champion.

Since 1998 she attended Sing'ore Girls High School near Iten, famous for producing Kenyan women athletes.

She attended the Kenyan trials for 1999 World Youth Championships, but as 400 m hurdles was not competed at the trials, she opted to take part in 800 m.[2] She finished second and was selected for the Kenyan team, but failed to reach the final of 800 m competition in World Youth Championships held in Bydgoszcz, Poland.

She managed to beat veteran runner Maria de Lurdes Mutola of Mozambique.

[6] On 24 May 2008 the 19-year-old Pamela Jelimo set a new Kenyan record of 1:55.76, beating the one previously held by Jepkosgei.

However, after a successful protest, she was allowed to run in the semi-finals[8] and eventually achieved silver medal, well behind the winner Semenya.