Background: Ulcerative colitis [UC] is an inflammatory disease of the colon with a relapsing-remitting course. Early diagnosis is crucial, and the presence of a screening test is of utmost importance. Bowel ultrasound could be used as a screening tool for UC. Aim of the work:To assess the diagnostic accuracy of bowel ultrasound in detecting disease activity and severity in adult patients with UC, compared with Ileocolonoscopy as the reference standard.Patients and methods: This prospective study included 42 adult patients with an established UC diagnosis for at least six months. All patients were subjected to full inquiry about their disease history, complete clinical examination, laboratory investigations, colonoscopy, and bowel ultrasound of the abdomen with Doppler mapping.Results: Colonoscopy revealed that 41% in remission and 59% in an activity. Thirty patients had left-sided, and 12 had an extensive UC. White blood cells, platelet count, erythrocyte sedimentation rate, and C-reactive protein significantly increased in patients with activity versus remission. But, hemoglobin concentrations significantly decreased. Colonic wall thickness significantly increased in patients with activity versus remission [5.17±0.74 vs. 2.57±0.24, respectively]. Hypoechogenic or lost colonic wall pattern, enlarged mesenteric lymph nodes and Doppler colonic wall-flow significantly increased in cases with disease activity versus remission [32.0%, 24.0% and 72.0% vs 0.0%, 0.0% and 0.0% respectively]. Conclusion:Transabdominal bowel ultrasound had a beneficial role in diagnosing ulcerative colitis. It could be used as a screening tool for rapid diagnosis or follow up of treatment.