Fifty-seven males, previously treated for malignancies in childhood, and who refused to masturbate for semen analysis, were submitted to hormonal, ultrasonographic, and Doppler evaluation to assess the effects of chemotherapy/radiotherapy on gonadal function. Nineteen normal healthy fertile males served as controls. In the studied population, FSH was inversely correlated with testicular volume and directly correlated with testicular vascularization, suggesting that ultrasonographic and color Doppler scanning of the testes may be used, if a sperm count is not available, to indirectly assess the gonadal function.