Prevalence of autistic spectrum disorders (ASD) in Oman is unknown. We conducted a cross-sectional study to estimate the prevalence of ASD among 0-14 year old children. Diagnoses were made as per DSM-IV-TR criteria and supplemented with information collected with the standard Childhood Autism Rating Scale (CARS) questionnaire. A total 113 cases of ASD were enumerated nationwide, indicating an overall prevalence of 1.4 (95% CI 1.2, 1.7) cases per 10,000 children aged 0-14 years. More prevalent cases were among boys (75%) and among low-income families. Ritualistic interests were more common among girls as an onset-symptom compared to boys (p = 0.03). The reported low prevalence of ASD in Oman is likely due to under-diagnosis and under-reporting.