We examined the association between self-reported symptoms of asthma and allergic rhinitis and self-reported exposure to motor vehicle traffic in adolescents in Münster, Germany. A total of 3,703 German students age 12-15 years completed a written and video questionnaire in 1994-1995. We found positive associations between both wheezing and symptoms of allergic rhinitis during the past 12 months and self-reported frequency of truck traffic. The sex- and age-adjusted prevalence odds ratios and 95% confidence intervals (CI) for truck traffic, contrasting the categories "frequent" and "constant" against "never," were, for wheezing obtained by written questionnaire: 1.53 (95% CI = 1.15-2.05) and 2.15 (95% CI = 1.44-3.21); for wheezing obtained by video questionnaire: 1.61 (95% CI = 1.26-2.07) and 2.47 (95% CI = 1.74-3.52); and for symptoms of allergic rhinitis: 1.71 (95% CI = 1.36-2.15) and 1.96 (95% CI = 1.40-2.76), respectively. We found a similar positive association with self-reports on traffic noise. Putative confounding variables, including indicators of socio-economic status, smoking, etc, did not alter these associations substantially. The results correspond closely with findings of a survey carried out in 1991 in Bochum, Germany. Our results support the hypothesis that exposure to motor vehicle traffic is related to symptoms of asthma and allergic rhinitis in children, but we cannot rule out misclassification due to self-reports of traffic exposure.