Menstruation is a unique natural phenomenon seen among the female human beings. It is very much a topic of science related to birth. However, it has always been subjected to taboos and myths that form many aspects of socio-cultural lives. In one hand, menstruation has been revered as a divine phenomenon. On the other hand, female beings are lowly held because of menstruation in many parts of the world. In India, we find both the practices deeply rooted in many traditional and religious beliefs. Ambuvāchῑ, a spiritual practice prevalent in the Indian state of Assam, manifests these two contradictory ideas. It secludes the menstruating goddess like any common woman during the first three days of her menstruation. On the contrary, on the day of nibritti, angavastra or the piece of cloth which is supposed to be wet with menstrual blood is distributed as Prasad among the devotees. Apart from Ambuvāchῑ, other festivals like Keddasa festival, Raja Parba, Rituals at ChengannurMahadev Temple etc. also are centered on the concept of menstruation. In this article it is being tried to evaluate the practices of Ambuvāchῑ and other festivalsand find the socio-cultural basis of such festivities.)