Back ground: Primary dysmenorrhea is thought to afflict 50-90% of the world's young female population.

Methods: The prevalence of primary dysmenorrhoea was found to be 51%. Majority (76%) of the students had severe and very severe dysmenorrhoea before muscle stretching exercise whereas majority (57%) of the students had moderate dysmenorrhoea after muscle stretching exercise in Group II. In Group I, 70% of the students had severe and very severe dysmenorrhoea. A significant difference was found in pain score (t=8.4, P<0.005) and associated symptoms (t=9.086, P<0.005) before and after muscle stretching in Group II. A significant difference was found in pain (t=3.58, P<0.05) and symptoms of dysmenorrhoea (t=1.76, P<0.005) in Group I and Group II.

Interpretation: The results show that yoga therapy is effective in reducing dysmenorrhoea.