The present study examines whether physical activity level (hours per week) among children with and without asthma are associated with the prevalence of reported wheezing and whistling in the chest in the last 12 months. The data are based on a survey of school children, aged 7-16 years (n = 2188), in Oslo in 1994 that employed the ISAAC questionnaire. In children reporting asthma, wheezing and whistling in the chest in the last 12 months was less prevalent among inactive children (66.7%) compared to those who exercised (89.4%) (p = 0.05). The prevalence of wheeze also differed among inactive (4.4%) and active (8.8%) children not reporting asthma (p = 0.02). Positive associations between physical activity and wheezing and whistling in the chest remained present using multiple logistic regression analysis adjusting for sex, age and atopy. Children who are engaged in sports or exercise seem to report asthma symptoms differently than inactive children. These findings raise the question whether level of physical activity could affect some of the variability in reported asthma symptoms when such morbidity is measured as 'wheeze in last 12 months'.