Subtotally pancreatectomized (95 %) white male rats do not show sexual disturbances during the prediabetic stage. During the stage of manifest diabetes, disturbances appear, and their severity increases progressively with the duration and degree of hyperglycemia. Fasting blood sugar levels from 120 mg% to 200 mg% are associated with disturbances of sexual behavior, with diminution of insemination capacity, and reduction or abolition of the biosynthesis of androgens in vitro. Blood sugar levels higher than 200 mg % are associated with an increase in the previous mentioned changes and lesions of the testicular tubules that can progress up to the complete abolition of the germinal epithelium. In summary, the sexual changes in the male 95 % pancreatectomized rat are related to the level of hyperglycemia. The mechanism is unknown. 1 Supported by Grant M 66.0126 from the Population Council