To evaluate the role of cisplatinum in the treatment of advanced non-small cell lung cancer, 48 patients received either a doxorubicin (adriamycin) 50 mg/m2 I.V., cyclophosphamide 300 mg/m2 I.V., lomustine (CCNU) 50 mg/m2 p.o., vincristine (oncovin) 1.2 mg/m2 I.V. (ACCO) combination or the same drugs plus cisplatinum 50 mg/m2 I.V. (PACCO) in a prospective sequential trial. No patient had received prior chemotherapy. Patients receiving the two regimens were comparable with regard to median age, performance status, histologic subtype, disease extent, and weight loss. Objective response frequency was only 5% in the initial 20 patients receiving ACCO treatment compared to a response frequency of 28% (7% complete) in the 28 patients receiving cisplatinum in the PACCO treatment arm (p less than 0.06). Patients achieving objective response lived significantly longer than nonresponders (9.1 months vs. 3.8 months, p less than 0.05). Although median survival was similar on the two regimens (6.1 months for ACCO vs. 7.6 months for PACCO), more than four times as many patients were alive after 1 year in the PACCO treatment group (24% vs. 5%). Predominant toxicity consisted of moderately severe nausea and vomiting (63% on PACCO vs. 34% on ACCO, p less than 0.05) and myelosuppression with WBC less than 3,000/mm3 occurring in the majority of patients on both regimens. These results suggest cisplatinum addition to a doxorubicin, cyclophosphamide, lomustine, and vincristine combination may be associated with increased 1-year survival in the non-small cell lung cancer patient population.