Background: Autistic disorder (AD) is one of the most serious psychiatric disorders in children and adolescents. Identification of relevant risk factors is a main step in disease management. Objectives: The aim of this study was to determine probable risk factors for AD. Methods: This case-control study was carried out in the Tabriz University of Medical Sciences. By convenience sampling method, 115 children with autism were selected from Rehabilitation Center of Autism Society in Tabriz, Iran. Moreover, 112 children were selected as control. AD was diagnosed based on DSM-IV-TR criteria by a child and adolescent psychiatrist. Results: Asthma, epilepsy, microcephaly, hearing / vision impairments, allergy to milk/wheat, side effects of rubella vaccines, and language disorders in the immediate family members including siblings, parents’ low education and lack of breastfeeding were more prevalent in AD children. Based on the logistic regression results, mothers’ low education [Exp (B) = 4.59, CI = 2.13-9.87, P < 0.001] and lack of breastfeeding until the age of two [Exp (B) = 2.91, CI = 1.54-5.50, P < 0.01] were the predictors of AD. Conclusions: Parents’ education and lack of breastfeeding until the age of two could predict AD in children. Improving educational system and increasing families’ awareness about benefits of breastfeeding will be valuable.