OBJECTIVE This multicenter, randomized phase III clinical trial evaluated the efficacy of etoposide plus carboplatin (EC) versus etoposide plus cisplatin (EP) in good-risk germ cell tumor (GCT) patients. METHODS Between October 1986 and December 1990, 270 patients with good-risk GCTs were randomized to receive four cycles of either EP or EC. The etoposide dose in all patients was 100 mg/m2 on days 1 through 5. EP patients received cisplatin at 20 mg/m2 on days 1 through 5 and therapy was recycled at 21-day intervals. For EC patients, the carboplatin dose was 500 mg/m2 on day 1 of each cycle and the EC recycling interval was 28 days. RESULTS Two hundred sixty-five patients were assessable: 131 patients treated with EC and 134 treated with EP. One hundred fifteen of 131 assessable patients (88%) treated with EC achieved a complete response (CR) versus 121 of 134 patients (90%) treated with EP (P = .32). Sixteen patients (12%) treated with EC relapsed from CR versus four patients (3%) treated with EP. Therefore, 32 patients (24%) who received carboplatin experienced an event (incomplete response [IR] or relapse) compared with 17 of 134 patients (13%) who received cisplatin (P = .02). At a median follow-up of 22.4 months, event-free and relapse-free survival were inferior for patients treated with EC (P = .02 and P = .005, respectively). No difference in overall survival was evident (P = .52). CONCLUSIONS Two-drug therapy with EC using this dose and schedule was inferior to therapy with EP. Cisplatin remains as the standard platinum analog in the treatment of patients with good-risk GCTs. Carboplatin should be restricted to investigational trials in GCT.