The high cure rate among young men with metastatic testicular germ cell tumors heightens the issue of late treatment toxicity. Conventional combination chemotherapy based on cisplatin can be expected to cure 85% to 90% of patients with metastatic disease; however the cost of this success includes severe treatment side effects, including irreversible renal damage and the risk of neurotoxicity and ototoxicity. Carboplatin was investigated as a replacement for cisplatin in the treatment of these tumors because of its reduced toxicity. The Royal Marsden Hospital pilot studies have included 76 patients treated for metastatic nonseminoma with the combination carboplatin/etoposide/bleomycin between 1984 and 1988. The median follow-up at time of analysis was 24 months. The complete remission rate was 95% and the overall cause-specific survival was 98.5%. Also, 33 patients treated with single-agent carboplatin for advanced metastatic seminoma were followed for a median of 36 months. The actuarial progression-free survival was 79%, and 91% of patients were alive and disease-free. The results of these studies indicate that carboplatin has activity equivalent to cisplatin in germ cell tumors of the testis and is less toxic.