Aim: To assess and compare the oral health status of preschool children with and without autism spectrum disorders. Methods: A random sample of 347 preschool children with autism spectrum disorder was recruited from 19 Special Child Care Centres in Hong Kong. An age- and gender-matched sample was recruited from mainstream preschools as the control group. Dental caries status, gingival health status, tooth wear, malocclusion, dental trauma and oral mucosal health were assessed and compared between the two groups. Results: It was feasible to conduct a comprehensive oral health screening among 74.1% (257) of the children with autism spectrum disorder. The mean age was 59 ± 10 months (range from 32 to 77 months), of whom 84.4% were males. Children with autism spectrum disorder had better gingival health than children without autism spectrum disorder (mean plaque score and gingival score p < 0.001). Children with autism spectrum disorder had less caries experiences than children without autism spectrum disorder (mean decayed, missing and filled surfaces and decayed surfaces, p < 0.05). Children with and without autism spectrum disorder had similar prevalence of tooth wear, malocclusion, dental trauma experience and oral mucosal lesions (p > 0.05). Conclusion: Differences in oral health status exist among preschool children with and without autism spectrum disorder. Preschool children with autism spectrum disorder exhibited lower caries experiences and better gingival health than children without autism spectrum disorder.