From the population covered by the Lombardy Cancer Registry (northern Italy), all 2,259 lung cancer patients diagnosed from 1976 to 1981 were followed through 30 November 1989. The length of follow-up ranged from eight to 13 years. A special investigation on long-term survivors showed that a negligible proportion (0.01 percent) of errors occur in determining life status when an active follow-up is adopted. Age, stage, and histotype were found to be statistically significant, independent, prognostic factors in multivariate analysis both by the Cox model and by a model considering the relative survival. Observed survival was 29 percent at one year after diagnosis, 13 percent at two years, eight percent at three years, five percent at five years and two percent at 10 years. Survival decreased with age, but the youngest patients of both sexes showed lower survival compared with immediately subsequent ages. Among morphologically confirmed tumors, epidermoid carcinomas and adenocarcinomas showed the highest survival (38 percent and 33 percent at one year, respectively); small cell carcinomas showed the poorest prognosis (one-year survival, 23 percent). Beyond the second year after diagnosis, differences between histotypes became slighter. Survival according to stage showed a decreasing pattern from limited to advanced tumors, one-year figures being 41 percent for localized tumors, 27 percent for regional metastasis, and three percent for distant metastasis. Relative survival in Varese was compared with that reported by other cancer registries in Western countries: the variability noted could be related to different modalities of registration and to different distribution of clinical and demographic factors.