In the County of Uppsala, Sweden, a general health survey including a chest roentgenogram was operational from the late 1960s until the end of June, 1985. The screening was offered every 2 years and participation was about 70%. From the local cancer registry all cases of lung cancer during the period 1980-1990 aged 75 or less were obtained and their survival and mode of discovery investigated. Only WHO I-IV and undifferentiated cancers verified histologically were included. Twenty-eight cancers (11.5%) were discovered in the survey and these patients had a very good prognosis compared to those who presented with symptoms. During the health survey there were 35 of 244 (14.3%) who survived more than 4 years, and after the survey this figure was 34 out of 265 (12.8%), a nonsignificant difference. Survival for patients with squamous cell carcinoma or adenocarcinoma discovered in the health survey was much improved, and for these two groups combined the 4-year survival was 41.7% compared to 10.3% for those discovered by symptoms (P < 0.001). Thus, survival of patients with lung cancer of squamous cell or adenocarcinoma types can be improved by screening, but unfortunately, only few of the cancers will be discovered in this way, so the total impact of screening will be small.