Background: The prevalence of autism spectrum disorders (ASD) varies worldwide from 1.4/10 000 children in the Arabian Peninsula to 185/10 000 children of Asian population. In Europe, the highest prevalence has been observed in Sweden, while the lowest in Croatia (115/10 000 and 2-3/10 000, respectively). There have been no epidemiological studies on the prevalence of ASD in Polish population. The aim of our study was to assess the prevalence of ASD in children aged 0-16 years, inhabitants of West Pomeranian and Pomeranian regions. Material and Methods: In total, 2514 children (2038 males, 81.1%) were included. The estimates were based on the government registries, whereas data were obtained from Provincial Disability Services Commissions. Results: The prevalence of ASD in children aged 0-16 years varies between two regions of Poland--2/10 000 in West Pomeranian and 38/10 000 in Pomeranian region. Conclusions: The average prevalence of ASD was 35/10 000 children and was about 4-fold higher in males (P < 0.05). More studies are necessary.