OBJECTIVE This study evaluated whether occupational exposure plays a role for lung cancer at a very young age. METHODS In a pooled analysis of 2 German case-referent studies including 3498 incident cases among men and 3541 male population referents, a group of men (187 cases and 202 referents) aged > or =45 years was compared with a group of 2186 cases and 2146 referents aged 55-69 years. Occupational exposure to known (A list) or suspected (B list) lung carcinogens was assessed using job and industry codes, and exposure to asbestos was assessed using job-specific supplementary questionnaires. A conditional logistic regression was used to calculate the odds ratios (OR) and to control for smoking. RESULTS Asbestos exposure showed an odds ratio (OR) of 2.39 [95% confidence interval (95% CI) 1.41-4.04] for the younger group and 1.46 (95% CI 1.24-1.72) for the older group. Having ever worked in a job belonging to the A list as compared with never working in an A- or B-list job was associated with a significantly increased risk for the younger (OR 2.06, 95% CI 1.03-4.12) and older (OR 1.35, 95% CI 1.10-1.65) groups, adjusted for asbestos. Lung cancer risk for those working in A-list jobs at a very young age (under 16 years) was increased in the younger group (OR 6.14, 95% CI 1.41-28.01) in contrast to the older group (OR 1.19, 95% CI 0.91-1.63). CONCLUSIONS Occupational risk factors play an important role for lung cancer among young men. Early age at first exposure may favor an early age of the onset of lung cancer.