We obtained lifetime occupational and residential histories by telephone interview with 622 mesothelioma patients (512 men, 110 women) and 1420 population controls. Odds ratios (ORs) were converted to lifetime risk (LR) estimates for Britons born in the 1940s. Male ORs (95% confidence interval (CI)) relative to low-risk occupations for >10 years of exposure before the age of 30 years were 50.0 (25.8-96.8) for carpenters (LR 1 in 17), 17.1 (10.3-28.3) for plumbers, electricians and painters, 7.0 (3.2-15.2) for other construction workers, 15.3 (9.0-26.2) for other recognised high-risk occupations and 5.2 (3.1-8.5) in other industries where asbestos may be encountered. The LR was similar in apparently unexposed men and women (approximately 1 in 1000), and this was approximately doubled in exposed workers' relatives (OR 2.0, 95% CI 1.3-3.2). No other environmental hazards were identified. In all, 14% of male and 62% of female cases were not attributable to occupational or domestic asbestos exposure. Approximately half of the male cases were construction workers, and only four had worked for more than 5 years in asbestos product manufacture.