Five hundred men and 76 women all under the care of one physician at the London Chest Hospital were diagnosed as having bronchogenic carcinoma and admitted to a prospective survey between May 1966 and April 1978. The survey was completed in December 1984 when all but 19 of the 500 men had died. None was lost to follow up. The longest period of surveillance was 18 years 7 months, the shortest 6 years 8 months. The five-year survival of the group of 500 men was 7.6% (38), and 22% (32) for the 145 patients who had had resections. Of the 78 patients (63 men, 15 women) who had small cell carcinoma, only one survived 3 years; the others died in under 2 years, giving a median survival of 5 months. The median survival of the 21 untreated cases in this group of small cell carcinoma was 2 months.