The objective of the present study was to assess the prevalence of asthma and asthma-related symptoms in Finland. We also wondered whether chronic cough may be an indicator of occult asthma. Prevalence and characteristics of children with doctor-diagnosed asthma and chronic respiratory symptoms were investigated in 7-12 year old school children from eastern Finland by using a questionnaire on respiratory symptoms. In addition, skin-prick tests, flow-volume spirometry, and serum total immunoglobulin E (IgE) measurements were performed in children reporting chronic respiratory symptoms. The parent-reported prevalence of doctor-diagnosed asthma was 4.4%, of wheezing 5.4%, of attacks of shortness of breath with wheezing 4.6%, and of dry cough at night 12%. Children with dry cough only (n = 195) had less frequent parental asthma, self-reported allergies, daily respiratory medication, and moisture stains or molds at home than asthmatic children (n = 180), but these findings were more frequent than among asymptomatic children (n = 2,169). The prevalence of at least one positive skin-prick test result was 79% among the asthmatic children and 55% among children with dry cough only. There were no differences between the two symptom groups in serum total IgE levels and spirometric lung functions, except in maximal mid-expiratory flow (MMEF) values, which were significantly lower among children with asthmatic symptoms. The present results support the hypothesis that chronic cough may be an indicator of occult asthma. Therefore, to improve the sensitivity of respiratory questionnaires designed to detect asthma, they should also include questions on chronic cough.(ABSTRACT TRUNCATED AT 250 WORDS)