Objective: To investigate the prevalence of symptoms of allergic disorders, mainly bronchial asthma, allergic rhinitis and allergic eczema in school children in the Czech Republic. Methods: The questionnaire based on the standardised ISAAC questionnaire (International Study of Asthma and Allergy in Children) was distributed to pupils of two age groups in randomly selected schools in the Czech Republic. Children in the age group of 13 to 14 years completed the questionnaire at school, for children at the age of 6 to 7 years the parents completed the questionnaire at home. Results: 4251 questionnaires were completed (1827 in the older group and 2424 in the younger group), the response rate was 77.1 %. The estimated 12-month prevalence of wheezing was 13.2 % (15.9 % in the older group and 11.2 % in the younger group), the 12-month prevalence of exercise induced wheezing was 5.6 % (8.8 % and 3.1 %). The 12-month prevalence of four and more episodes of wheezing was 3.5 % (3.9 % and 3.0 %). The life prevalence of diagnosed asthma was 3.7 % (4.8 % and 2.9 %); 9.6 % of all children however used some type of asthma medication. Only 23 % of the children with wheezing in the last 12 months were diagnosed as having asthma. The overall 12-month prevalence of wheezing was higher in cities than in rural areas (22.5 % vs. 3.9 %). The prevalence of allergic rhinitis was 13.2 % (17.2 % and 10.2 %) and the prevalence of eczema in typical locations was 13.7 % (14.0 % and 13.4 %). We identified significant risk factors in children with diagnosed asthma. In 52.8 % of such families there was pet and a smoker was present in 36.3 % of these families. Conclusions: The prevalence of symptoms of bronchial hyperresponsiveness and asthma in Czech school children is rather high, there is still a substantial underdiagnosis of the disease and important risk behaviour of the families. This may lead to more severe disease and impaired prognosis.

        Key words: bronchial asthma, wheezing, eczema, allergic rhinitis, prevalence, risk factors