Gossypol dissolved in methanol (0.25 and 0.5 mg/ml) was gamma-irradiated at 0, 5, 10, and 20 kGy. The gossypol content was significantly reduced by irradiation in a dose-dependent manner. Ames test performed with nonirradiated and irradiated gossypol solutions was negative at the level of 0.1, 0.5, 1, 10, 50, and 100 microg gossypol/plate. At the gossypol concentration of 2.5 microg/ml, the blastocysts formation rate of mice embryo were decreased by a factor of two as compared with the control, but irradiation at 20 kGy increased the blastocysts formation, resulting in no difference from the control. Addition of gossypol to oil emulsion system or oil showed a prooxidative effect of lipids at the beginning stage by increasing 2-thiobarbituric acid reactive substances (TBARS) and peroxide value but irradiation of the gossypol solution decreased the oxidative changes significantly as compared with the nonirradiated one. Results indicated that irradiation decreased the gossypol concentration dissolved in methanol, resulting in a reduction of embryotoxicity in mice.