A total of 185 eligible patients with advanced inoperable squamous cell carcinoma of the head and neck were randomized into two groups; the cisplatin, methotrexate, bleomycin, and vincristine (CABO) group received cisplatin (50 mg/m2; day 4), methotrexate (40 mg/m2; days 1, 15), bleomycin (10 mg; days 1, 8, and 15), and vincristine (2 mg; days 1, 8, and 15) and the ABO group received methotrexate, bleomycin and vincristine in the same doses on days 1, 8, and 15. After three courses, patients in both arms received weekly methotrexate as maintenance therapy; those 34 patients with previously untreated locoregional disease went off the study because of subsequent locoregional treatment in form of radiotherapy +/- surgery. The complete response rate was 16% in patients receiving CABO, compared with 5% among patients given ABO. The corresponding overall response rates were 50% and 28%, respectively (P = 0.003). Among patients with recurrent or metastatic disease, progression was delayed in patients receiving CABO (median, 18 weeks) compared to those receiving ABO (median, 14 weeks) (P = 0.07), but there was no difference in survival time. Myelosuppression consisted mostly of leukopenia, which was seen in 67% of the CABO patients versus 47% in the other arm. Myelosuppression-associated infection and hemorrhage led to death in two patients in the CABO treatment group and six patients in the ABO treatment group. Nausea and vomiting, mostly of grades 1 or 2, occurred in 93% of the patients given CABO and 44% of those receiving ABO. Other toxic effects--neuropathy, alopecia, stomatitis, constipation, fever/chills, diarrhea, cutaneous alterations, and renal impairment--occurred equally in the two treatment groups. This study underlines the role of cisplatin in head and neck cancer, although no impact on survival could be demonstrated. It also supports indirectly the superiority of combination chemotherapy over single-agent treatment for this disease.