Twenty-four patients < 40 yr of age were diagnosed at Walter Reed Army Medical Center between 1971 and 1976 as having lung cancer. The youngest patient was 19 yr old. Only 1 was a nonsmoker. Most patients were symptomatic at the time of examination. The chest roentgenogram showed an infiltrate or consolidation in 9, a mass lesion in 13 and a pleural effusion in 1. Thirty-eight percent had adenocarcinoma, 21% had squamous cell carcinoma and 21% large cell carcinoma. Nineteen patients had stage II or III disease at the time of initial examination, and only 6 had resectable tumors. Survival rates were poor.