Our objective was to investigate exposure to physical exercise and trauma in patients with amyotrophic lateral sclerosis (ALS) compared to the general population. Previous studies in this area have yielded conflicting results. Using population-based ALS registries from Italy, the UK and Ireland, newly diagnosed patients with definite, probable or possible ALS were enrolled in a case- control study with two age- and sex-matched controls for each patient. Source, intensity and duration of physical activity and history of trauma were recorded. We here present the results of a pilot investigation. We studied 61 patients and 112 controls. Forty-one per cent of cases and 17.0% of controls (p = 0.001) had blue-collar occupations; 13.1% versus 3.6% reported strenuous physical activity at work (p = 0.05). Compared with controls, ALS patients had a longer exposure to work-related (10.7 vs. 7.3 years; p = 0.02) and sport-related physical exercise (9.6 vs. 5.2 years; p = 0.005). Three patients (0 controls) reported professional sports (p = 0.04). Traumatic events were similar. Blue collar occupation (OR 4.27; 95% CI 1.68-10.88) and duration of sport-related physical exercise (OR 1.03; 95% CI 1.00-1.05) were independent variables in multivariate analysis. We concluded that ALS is associated with physical exercise but not with traumatic events.