Gossypol acetic acid has been shown to have the effect of increasing the SCE frequencies in the spermatogonial cells of mice. This study further confirmed the genotoxic effects of gossypol acetic acid by investigating the dose-response relationships of gossypol acetic acid-induced SCEs in spermatogonial cells and bone marrow cells of mice. Twelve or over 12 mg/kg body weight of the dosage per day could increase the SCE frequencies of both bone marrow cells and spermatogonial cells. The increase of SCE frequency appeared to be directly correlated with the doses used at significant levels (p less than 0.001). Regression lines indicated that, in spite of cell type variation, the SCE induced was proportional to the dose of gossypol acetic acid.