To assess prevalence of malnutrition indicators among preschool children with autism spectrum disorder (ASD) a cross-sectional study was conducted among 128 Omani autistic children 3-5 years of age. Based on standardized z-scores, the overall prevalence of malnutrition was 9.2 per 100 preschool ASD children (95% CI 4.1, 11.6). The most common type of malnutrition was underweight (3.9; 95% CI 0.5, 7.3), followed by wasting (3.1; 95% CI 0.1, 6.1) and stunting (2.3; 95% CI 0.3, 5.0). Among boys, underweight and stunting were significantly higher than in girls, while wasting was more prevalent among girls. None of the participants showed evidence of overweight or obesity. The study indicates an overall tendency among autistic Omani children towards being malnourished. (Contains 2 tables.)