Tinospora cordifolia is widely used in Ayurvedic medicines. It is known for its immunomodulatory, antihepatotoxic, antistress and antioxidant properties. It has been used in combination with other plant products to prepare a number of Ayurvedic preparations. The present study was undertaken to evaluate the radioprotective effect of an aqueous extract of Tinospora cordifolia (TC) against (60)Co gamma radiation. Oral administration of TC 5 mg/kg body wt to Swiss albino mice 1 h and 15 days prior to whole body radiation exposure (8 Gy) produced a significant protection in terms of survival percentage. After oral administration of TC 10 mg/kg body wt/day to mice 7 days prior to whole body irradiation (8 Gy) there was no mortality until day 13 and 50% of the animals survived until day 30. Mice exposed to radiation (8 Gy) without TC pretreatment exhibited signs of radiation sickness such as anorexia, lethargy, ruffled hair, diarrhoea and these animals died within 14 days of irradiation. The results from the present study suggest that Tinospora cordifolia has a radioprotective effect in Swiss albino mice, thereby enhancing the survival of mice against a sublethal dose of gamma radiation.