To evaluate the clinical efficacy and safety of carboplatin for head and neck cancer, a phase II study was conducted in 21 institutions. Eighty-eight patients were entered into this trial, of which 70 were evaluable. Carboplatin was administered intravenously over 0.5-1 hr at the dose of 400 mg/m2 in good risk cases and 300 mg/m2 in poor risk cases. One patient achieved complete response(CR) and 13 achieved partial response(PR) with an overall response rate of 20%. In terms of response by histology, the response rate was 22% in cases of squamous cell carcinoma. The response rate was 26% in previously untreated patients and 16% in previously treated patients. One CR and 2 PR were achieved in 14 patients with prior cisplatin treatment. Toxicity was observed in 47% of the 70 evaluable patients. Nausea and vomiting were the most common toxicity observed (36%) followed by anorexia in 27%. Concerning hematologic toxicity, thrombocytopenia was noted in 32% and leukopenia in 29%. Elevation of BUN and creatinine was observed in only 2 cases and 1 case, respectively. It was concluded that carboplatin suggested activity similar to cisplatin, and also could be safely used at the outpatient level.