The reported high use of anti-asthmatic drugs in cross-country skiers prompted a study to assess the prevalence of self-reported asthma, asthma-associated symptoms and the use of anti-asthmatic medication among cross-country skiers. A self-administered questionnaire based on the Medical Research Council questionnaire was answered by cross-country skiers in the Swedish national ski team, in upper secondary school ski-classes and in the Swedish army (n=305). Controls (n=141) were pupils from regular classes in the same upper secondary schools. Skiers more often gave posi- tive answers to all questions on asthma and asthma-associated symptoms. The cumulative prevalence of asthma was 15% in skiers and 6% in controls. We conclude that the common use of anti-asthmatic drugs among cross-country skiers reflects a high prevalence of self-reported asthma and asthma-associated symptoms. The causes of these differences are un-known.