The present study aims to characterize the prevalence of autism spectrum disorders (ASDs) in Taiwan while examining the effects of age, gender, and urbanization on ASD occurrence. A cross-sectional study was conducted to analyze data from 895,639 random health insurance claimants who claimed medical services in the year 2007. Autism was defined using the ICD-9-CM Diagnosis Code 299.0 (autism, current or active). The prevalence of autistic cases was found to be 12.3% (10,868/884,771) in the general population, with the prevalence among males (19.2%) significantly higher than that among females (6%). With regards to age distribution, we found that the autistic group (mean age = 16.0 years) was significantly younger than the general population (mean age = 37.2 years). A logistic regression analysis found that age, gender, residence urbanization level and Bureau of National Health Insurance regional division all constituted influence factors for autistic occurrence. The results demonstrate the importance of taking into account age, gender, and geographical disparities in autistic prevalence in order to implement appropriate public health policies for the ASD population. (Contains 3 tables and 1 figure.)