BACKGROUND: Atopic dermatitis (AD) is a common condition in infancy which usually disappears by 3 years of age in a significant proportion of children. The prognosis is mostly determined by severity and presence of atopic sensitization. OBJECTIVES: To investigate prevalence of AD, comorbidities and risk factors in a population of preschool children aged 3-5 years. METHODS: Children in kindergartens were evaluated. The International Study of Asthma and Allergies in Childhood written questionnaire (WQ) was used, with additional questions on risk factors. Atopy was investigated by skin prick tests. RESULTS: One thousand, four hundred and two valid WQs (92% response rate) were returned for evaluation. The prevalence of AD symptoms in the last 12 months in the whole population was 18.1% (254 cases). Seventy-two per cent of these children presented AD-specific localizations. The prevalence of eczema as a doctor's diagnosis in the total population was 15.4%. Positive atopic sensitization was present in 18.6% of the total and in 32.2% of the AD study population, respectively. Multiple sensitivities were observed in 58.2% of sensitized children. The prevalence of sensitization demonstrated that the most common sensitizing allergens in children with AD were mites and grass pollen. Rhinitis symptoms and wheezing were present in 32.2% and 24.2%, respectively, of children with AD. Allergic sensitization to egg, cat, grass pollen and mites, as well as the presence of symptoms of rhinitis, and a positive family history of atopy were all significant risk factors for AD. CONCLUSIONS: The study demonstrates a high prevalence of AD and a close relationship with rhinitis symptoms. Significant risk factors for AD were sensitization to food or inhalant allergens as well as parental history of atopy.