For the last 10 years there is no data on the prevalence of asthma in Slovenian children. To ensure accurate and high-quality data we will conduct a cross-sectional survey Health Interview (HIS) and Health Examination Survey (HES) design type. Therefore, we first prepared the study protocol. To get the data for the HIS part of the study we developed a new questionnaire. The exposure to outdoor air quality will be evaluated from the National Air Quality network data. In Slovenia the problems with health data should be addressed with the common unified system at the national level.