Objective(s): to determine the effect of dietary pattern on gastrointestinal symptoms among children with autistic spectrum disorder. Methodology: A descriptive correlational study designed to determine the effect of dietary pattern on gastrointestinal symptoms among children with autistic spectrum disorder for the period of October 20th 2021 to May 15th 2023. A nonprobability, purposive , sample of (150) parent of children with autistic spectrum disorder is selected for the purpose of the study. All parents have signed consent form for their agreement to participate in the study and to ensure confidentiality, as well as to confirm the ethical considerations. A developed questionnaire is used for the purpose of the current study. The questionnaire is comprised of (4) parts that include: parents’ socio-demographic characteristics (15) item; children’s socio-demographic characteristics (12) item; dietary patterns (16) item and gastrointestinal symptoms (14) item. Content validity of the questionnaire is determined through panel of (20) expert in the fields of Pediatric Nursing, Pediatric Medicine and Community Health Nursing. Internal consistency reliability of the questionnaire is obtained through the use of split-half technique. Cronbach alpha correlation coefficient is computed for such reliability; (r=0.81) for dietary patterns and (r=0.78) for gastrointestinal symptoms. Data are collected through the use of the study questionnaire. Data are analyzed through the use of the descriptive statistical data analysis approach of frequency, percent, mean, standard deviation, total scores and range and inferential statistical data analysis approach of multiple linear regressions. Results: The study findings indicate that children have experienced problems with their dietary patterns and such patterns have highly significant effect on gastrointestinal symptoms among children with autistic spectrum disorder evidenced by highly significant p-value of (0.001). Conclusion: The study confirms that there is highly significant effect between dietary patterns and gastrointestinal symptoms among children with autistic spectrum disorder.