Objective: In this study, we aimed to evaluate typically developing siblings of children diagnosed with autism spectrum disorder (ASD) in terms of depressive features and quality of life. In addition, the effect of special education interventions/psychopharmacological treatments of children diagnosed with ASD on the findings of siblings was evaluated.

Material and Method: One hundred fifty typically developing siblings of 150 cases who diagnosed with ASD (case group) and 50 control cases typically developing (control group) were included. Childhood Autism Rating Scale for children diagnosed with autism spectrum disorder was performed. The Pediatric Quality of Life Questionnaire was used to evaluate quality of life. Depressive features were evaluated with Children\'s Depression Inventory (CDI).

Results: In the analyzes performed without considering the treatment status, CDI scores were significantly higher in the case group than in the control group. (p <0.001). In the case group, the significantly lower quality of life scores were found in all domains of the children\'s selfreported quality of life forms than the control group (p <0.001). In the analyzes performed according to the treatment status, the highest depression score and the lowest quality of life score were found in the siblings of children with ASD who did not receive regular treatment. There was no significant difference in quality of life parent forms between the groups.

Conclusion: The presence of an individual with ASD in the family and lack of treatment support seem to adversely affect the lives of typical siblings. Further longitudinal studies with larger samples are needed.