The present study was conducted: a) to confirm data from others describing a radioprotective capacity of DMSO in mice; b) to establish whether this protective behavior could be evidenced in an in vitro chemical system utilizing bovine crystalline protein as target. Heterozigous female albino mice were used for the 30-day-survival studies after 9 Gy sup(60)Co gamma irradiation (dose rate: 4.5 Gy/min) injected 1 h prior with 2000 mg/kg DMSO intraperitoneally. Total body weight curves during the same period were also analysed. For the molecular level studies 1 M DMSO was added to a series of aqueous protein solutions from bovine lens and 10 min later irradiated with 5 different doses from 5,000 to 25,000 Gy sup(60)Co (average dose rate 14 Gy/min). After irradiation, spectrophotometric reading at 600 nm and free thiol group determinations were performed in order to evaluate the radiation-induced modifications. (author).