The aim of the present study was to compare the adjustment difficulties of siblings of children with autism spectrum disorder, intellectual disability, and typically developing children. The statistical population of the present study included all siblings of children with autism spectrum disorder, intellectual disability, and typically developing children in Shiraz, Iran. The sample consisted of 141 siblings (49 siblings of children with autism spectrum disorder, 42 siblings of children with intellectual disability, and 50 siblings of typically developing children). The Strengths and Difficulties Questionnaire (SDQ) [Goodman, 1997. 'The strengths and difficulties questionnaire.' "Journal of Child Psychology and Psychiatry" 40: 791-799.] was used for measuring the adjustment difficulties. Analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA) tests were used for data analysis. The results showed that adjustment difficulties and three subscales of adjustment difficulties (emotional symptoms, hyperactivity, and peer relationships) of siblings of children with autism spectrum disorder and intellectual disability were significantly higher than those of siblings of typically developing children. Furthermore, no significant difference was found between the study groups in terms of conduct problems. Therefore, it is essential to design and implement preventive and interventional programmes to improve the adjustment difficulties of siblings of children with disabilities.