Fifty-one patients with metastatic non-oat cell carcinoma of the lung were treated with a combination of cis-dichlorodiammineplatinum(II) and hexamethylmelamine. The overall response rate (all cell types) was 16%. Four of 20 patients with adenocarcinoma had a partial response and an additional five patients classified as having stable disease had tumor regression less than 50%. The median survival of responders and of those with stable disease (all types) was 8 and 7 months respectively, significantly longer than the median survival of patients who progressed (median survival, 2 months [P less than 0.05]). The major dose-limiting toxicity was nausea and vomiting in over half of the patients; hematologic toxicity and peripheral neuropathy were the other adverse effects of the combination.