Background: Early diagnosis of intestinal obstruction is critical for preventing subsequent complications. In this study, we compare the accuracy of plain abdominal X-ray and ultrasound imaging among children with intestinal obstruction, in terms of the diagnosis of obstruction and its underlying causes.Methods: This analytical cross-sectional study was performed at Akbar Children’s Hospital of Mashhad, Iran, in ۲۰۱۹-۲۰۲۱. Children with clinical manifestations of bowel obstruction underwent abdominal ultrasound examination and plain abdominal X-ray imaging, and the diagnostic findings were compared with the final definite diagnosis. Radiologic signs of obstruction were bubble signs in obstructions until the jejunum, and sausage-shaped air-filled bowel in obstructions of the rest of the bowel. The ultrasound signs were fluid-filled dilated loops, tubular or sausage-shaped dilated bowels, parallel valvulae conniventes (stack of coins), the to-and-fro motion, and the cause of the obstruction.Results: Overall, ۶۰ children with a mean age of ۳.۰۵ ± ۰.۸۷ years were studied. Post-operative adhesion was the most common cause of obstruction (۲۸%). Plain radiography revealed a normal pattern in ۱۵% of cases, bubble sign and/or decreased abdominal gas pattern in ۱۵% of patients (high-level obstruction), and sausage-shaped pattern of low-level obstruction in ۷۰% of cases, with ۷۲% accuracy. The sonographic signs of bowel obstruction were seen in all patients, with ۹۶.۶% accuracy. The cause of obstruction could be determined in ۹۱% of patients, with ۹۱.۶% accuracy.Conclusion: Plain abdominal X-ray had a normal pattern in ۱۵% of bowel obstructions while sonography revealed all obstructions with ۹۱.۶% accuracy. Therefore, ultrasound imaging can be used as the preferred imaging modality to diagnose gastrointestinal tract obstructions.