The purpose of this study was to compare stress, anxiety, depression and sleep quality in mothers of children with Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD), and Mental Retardation. The method of this study was descriptive and comparative. The statistical population of this study consisted of mothers of children with ASD, ADHD and mental disability residing in Arak. The sample consisted of 20 mothers with children with ASD, 32 mothers with children with ADHD and 32 mothers of children with Mental Disability. They completed the Depression, Anxiety, and Stress Scale (DASS-42) and Sleep Quality Index (PSQI). Findings indicate that there is no significant difference in the level of stress experience between the three sample groups. But there was a significant difference (0/001) in experience of anxiety, depression and sleep quality. From the above findings, it can be concluded that the birth of children with neurodevelopmental disorders is one of the main causes of psychological problems and experiences of anxiety, stress, and depression and reduced sleep quality in their mothers. To help them, it is recommended to consider group therapy sessions to teach coping skills with the conditions of stress, emotional exhaustion, and so on.