Withania somnifera Dunal is a member of Solanaceae family and most commonly known as Ashwagandha, Indian ginseng or winter cherry. It has been used in Ayurveda, in Indian traditional medicine. It is classified as a Rasayana (rejuvenation) helpful in increasing longevity and vitality, used for cardiovascular diseases treatment as herbal tonic. Human can consume it either as a single herb or an ingredient of polyherbal or herbomineral formulations. This chapter deals with various bioactive substances found in Ashwagandha and their use in the treatment of various diseases. Drugs obtained from Ashwagandha are anti-inflammatory, anti-arthritic, cardioprotective, anti-stress, tranquilizer types sedative activity, hypoglycemic, thyro protective activity. This chapter may help for the further evaluation of the Ashwagandha for the cure of the ailments which are threat to human being.