Withanolides are a group of naturally occurring oxygenated ergostane type steroids, having lactone in side chain and 2-en-1-one system in the ring. Withanolides are present in medicinal plants of Solanaceae family. Formulations based on these medicinal plants are widely used in Ayurveda and traditional Chinese medicine. Withanolides have shown a wide range of pharmacological activities including hypno sedative, immunomodulatory, anti-inflammatory, antiarthritic, angiogenesis inhibitor, anticholinesterase, antioxidant, antibacterial and above all, antitumour. Withaferin A is the best studied withanolide as far as pharmacological investigations are concerned. The present review summarises the investigative work carried out on bioactive withanolides.