Objective: To review the prevalence of Gastrointestinal symptoms among children in King Salman Armed Forces (KSAF) hospital-Saudi Arabia, Tabuk. Materials and methods: This study was a retrospective study, which conducted among autism children who visited King Salman armed forces hospital-Saudi Arabia, Tabuk from January 2016 to December 2020. All patients who aged from 2 to 14 years and diagnosed to have autism by DSM-5 criteria and by the assessment card were included in the study. All data was analyzed using the SPSS version 23.0 program (SPSS Inc, Chicago, IL). Results: The sample was 91 children diagnosed as ASD, 60.4% of them were >= 7 years, and 39.6% were < 7 years, 73.6% were males. Regarding autism symptoms; 44% delayed speech, 27.5% excessive movement, 4.4% convulsions, 15.4% other symptoms and 8.8% nothing. Most of them (81.3%) suffered at least one gastrointestinal symptom. GI symptoms were selective eating, diarrhea, diarrhea number per day, constipation, difficulty in defecation or pain during defecation, from large stools, a low stool frequency, defecating on himself, blood in stool, having very foul-smelling stools, and the presence of undigested pieces of food in the stool with the prevalence of 73.6%, 28.6%, 24.2%, 41.8%, 29.7%, 30.8%, 36.3%, 23.1%, 6.6%, 52.7% and 35.5% respectively. Conclusion: The prevalence of GI manifestations among autism children was 81.3% which was a relatively high when compared with the pervious similar studies. Selective eating, having very foul-smelling stools and constipation were the most common GI symptoms.