Background: IBD, occasionally referred to as "chronic inflammatory bowel disease" including Crohn's disease, ulcerative colitis (UC), and other gastrointestinal disorders are included in this group. Aim of the Work: The aim of our study was to assess serum resistin level in disease activity and remission in patients with ulcerative colitis disease. Patients and Methods: A cohort study for 6 months on 40 Egyptian patients presented with ulcerative colitis disease over 18 years old visiting the Outpatient Clinics or admitted in Ain Shams University Hospitals. Results: The present study revealed a highly significant elevation of serum resistin in active ulcerative colitis patients (p-value <0.001). There was direct relationship between the activity of ulcerative colitis and serum resistin. Resistin was positively correlated with inflammatory markers (CRP and ESR) in UC patients. And there was negative relation between resistin and Hb, fecal calprotectin. Conclusion: Serum resistin is a useful non-invasive test that was used to monitor disease activity in patients with ulcerative colitis. It positively correlated with inflammatory markers (CRP and ESR). Other studies should be done on larger size of participants to determine the the role of serum resistin as a marker of disease activity in patients with inflammatory bowel disease.