Background: Autism spectrum disorder is a neurodevelopmental disorder associated with symptoms that include persistent deficits in social communication and social interaction across multiple contexts and restricted, repetitive patterns of behavior, interests, or activities. Aim: This study aimed to assess mothers' knowledge, practice and attitude regarding Autistic children. Study design: Descriptive research design was used in this study. Sample: Purposive sample include 197 mothers of autistic children. Setting: In child psychiatry out-patient clinic at Tanta university hospital, El-Gharbia governorate, Egypt. Tools: One tool included 4 parts: 1st: Sociodemographic data for mothers and child, 2nd: Mothers' knowledge, 3rd: Mothers' reported practice. 4th: Attitude of the mothers. Results: The study result revealed that, 50 % of studied sample had poor knowledge. While 55 % of studied sample had unsatisfactory reported practice. 30 % of studied sample had negative with attitude. Conclusion: Most of the study sample had poor total knowledge about the autistic children, also most of them had satisfactory total practice regarding autism and majority of the studied sample had positive attitude about the autism. There is statistically significant relation between mothers' sociodemographic data and their total knowledge, total practice, total attitude regarding their children with autism. Recommendations: Designs health education program to mother about management their autistic children.