Motor stereotypies are frequently reported in individuals with autism spectrum disorder, but determinants of stereotypies remain poorly understood. In this study, a randomized sample of children with diagnosis of autism spectrum disorder was investigated to identify the prevalence and determinants of stereotypies. A total of 134 children who carried the diagnosis of autism spectrum disorder were included (aged 2.3-17.6 years; 79.1% male). Stereotypies were classified during a standardized protocol with video recording. The prevalence of stereotypies was 56.7%. Among 1198 captured stereotypies, hand/arm stereotypies were the most frequent. Thirty-five morphology patterns were identified, the most frequent being hand flapping, tapping, and jumping. In univariate analysis, an association was found between stereotypies and younger age (odds ratio = 0.74), developmental delay, or intellectual disability (odds ratio = 5.25), being nonverbal (odds ratio = 0.06), epilepsy (odds ratio = 3.89), Autism Diagnostic Interview--Revised-A score (odds ratio = 1.17), Autism Diagnostic Interview--Revised-C score (odds ratio = 1.25), and Autism Diagnostic Observation Schedule--2 score (odds ratio = 1.65). After multivariate analysis, only younger age, being nonverbal, and Autism Diagnostic Interview--Revised-A and Autism Diagnostic Observation Schedule--2 scores remained as determinants of stereotypies. The prevalence of stereotypies in autism spectrum disorder was close to the values obtained in a previous meta-analysis and seems to represent a valid value. The combination of younger age, being nonverbal, and autism severity seems to increase the odds of stereotypies.