Background : Ulcerative colitis is an idiopathic inflammatory condition of the colon which results in diffuse friability and superficial erosions on the colonic wall associated with bleeding. We will assess how faecal calprotectin can be used as a non-invasive tool to aid referral to GI services, and how this improves cost effectiveness of resource allocation through reduction of unnecessary colonoscopies. Objective:To determine the diagnostic accuracy of fecal calprotectin in prediction of ulcerative colitis in patients of inflammatory bowel disease. Study Design: A Cross Sectional Validation Study. Setting: Department of Gastroenterology, ATH, Abbottabad. Duration of Study: This study was conducted from 10th May 2021 to 10th November 2021. Methods: A total of 313 patients of both gender with inflammatory bowel disease were included in the study. Ulcerative colitis was noted as per 2 operational definition from fecal calprotectin and histopathology as positive/negative on especially designed proforma. Results: In this study age range was 18 to 50 years with mean age of 41.530±5.63 years and mean duration of complaints was 11.258±3.72 months. Fecal calprotectin diagnosed 54(17.3%) patients while histopathology diagnosed 40(12.8%) patients with ulcerative colitis.Fecal calprotectin has shown sensitivity of 70%, specificity 90.5% and diagnostic accuracy by 88%, PPV 51.9% and NPV 95.4% in diagnosisof ulcerative colitis. Conclusion: fecal calprotectin is a highly reliable predictor of endoscopic activity in IBD patients. It performs better for ulcerativecolitis prediction.