Because treatment with surgery and combination chemotherapy produces a high cure rate in young men with osteosarcoma, their subsequent reproductive function is an important concern. Semen analyses of osteosarcoma patients, therefore, were performed before, during, and after treatment with the PADIC regimen consisting of cisplatin, Adriamycin (doxorubicin), and dacarbazine or, in some cases, the PADIC regimen plus additional drugs. Results showed that semen volume was not affected and that sperm motility was reduced only during treatment. Although nearly all patients were rendered azoospermic during treatment, sperm production resumed in 30 of 32 patients examined at least 2 years after treatment. Analysis with correction for censored data indicates that, in 78% of treated men, sperm counts will return to more than 10 million/ml. The percentage of men whose sperm counts recovered to normal was lower for those receiving cisplatin dosages greater than or equal to 600 mg/m*; no trends were observed with Adriamycin and dacarbazine dosages. The inclusion of additional drugs such as methotrexate, bleomycin, dactinomycin, or cyclophosphamide (<4 g/m2) did not significantly affect the recovery of spermatogenesis. We conclude that the risk of long-term infertility from treatment with the PADIC regimen is low.