Niusha Carmen Mancilla Heredia (born 19 January 1971 in Cochabamba)[1] is a Bolivian former middle and long-distance runner.

She is a two-time South American silver medallist in the 1500 metres and competed three times at the IAAF World Indoor Championships over that distance.

Mancilla began competing in middle distance events from a young age and was the 800 metres bronze medallist at the 1984 South American Youth Championships in Athletics.

[8] In the outdoor season she claimed her first major senior medal, a silver over 1500 m at the 1997 South American Championships in Athletics.

[13] Her best performances the following year all came at the 2001 Bolivarian Games, where she completed a triple gold medal sweep in the 800 m, 1500 m and the 3000 metres steeplechase.

[8] At the 2003 South American Championships in Athletics Mancilla won her second and final continental track medal with a runner-up performance in the 1500 m (she was also fourth over 800 m).