Family history data from a case-control study of lung cancer conducted in the United Kingdom between 1999 and 2004 were analysed to estimate familial risks of the disease. Comparison of lung cancer prevalence in first-degree relatives of 1,482 female lung cancer cases and 1,079 female controls was undertaken using logistic regression adjusting for age and tobacco exposure. Overall, lung cancer in a first-degree relative was associated with a significant increase in the risk of lung cancer [odds ratio (OR) 1.49; 95% confidence interval (CI), 1.13-1.96]. For cases with early onset of the disease (< 60 years), the OR of lung cancer was 2.02 (95% CI, 1.22-3.34). Having 2 or more affected relatives was associated with an OR of 2.68 (95% CI, 1.29-5.55), with a significant trend in risk according to the number of relatives affected (p = 0.001). An increased risk of lung cancer associated with family history of the disease was observed when analysis was restricted to lifetime nonsmokers, although this did not reach significance (OR 1.23; 95% CI, 0.65-2.31). Results confirm previous findings and support the role of a familial predisposition to lung cancer.