Sixty-eight evaluable patients with advanced squamous cell carcinoma (48), large cell carcinoma (2) and adenocarcinoma (18) of the lung were treated with a six-drug regimen delivering two monthly alternated combinations. The combinations were cisplatin, adriamycin and cyclophosphamide (CAP) and methotrexate, etoposide and CCNU (MEC'). Following a minimum of two courses, the overall response rate was 22% (confidence limits, 12% to 32%) (15/68, 2 complete responses and 13 partial responses); 47% (32/68) had stable disease and 31% (21/68) had progressive disease. The responses lasted a median of 3 months (range, 1-15 months). The actuarial median survival was 11 months in responsive patients, 10 months in stable disease patients, and 5 months in progressive patients. The overall median survival obtained was 9 months (range, 2-28+ months). Toxicity was minimal, and subjective tolerance of the treatment appeared good. However, this alternating program did not improve response rate or survival.