Abstract : Ulcerative Colitis (UC), is a type of inflammatory bowel disease (IBD), recent research and studies showed an association between H. pylori infection and IBD. This study was conducted to evaluate the association between H. pylori infection and the severity of ulcerative colitis. A cross-sectional descriptive study was conducted at Fayhaa Teaching Hospital, Gastrointestinal center, Basrah, the southern part of Iraq from August 2021 to February 2022, on 52 patients with Ulcerative colitis. The included patients were categorized into two main groups according to the Helicobacter pylori stool antigen status. Before the official study conduction, a simple pilot study was conducted on 52 patients. Statistical calculations were done using Statistical Package for the Social Sciences version 25 (SPSS Inc.) and P-values <0.05 were accepted as statistically significant. The current study included 52 patients with a mean age of (31.60± 11.54), and (53.8%) of the studied population were males, the mean duration of the disease was 3.29± 2.64 years. Out of the studied groups, (53.8%) were diagnosed with H. pylori-positive antigen, and (46.2%) with negative antigen. The Truelove and Witt’s Severity Index for Ulcerative Colitis has classified the cases into three main categories (mild, moderate, and severe), the mean age and duration of the disease were slightly higher among the severe group (34.29± 12.40, 3.86± 1.67) followed by the mild group (31.44± 12.29, 3.56± 3.32). Most males developed a moderate category (72.3%), while most females were classified as a severe class (71.4%). Also, it was clearly shown that most of the patients with positive H. pylori Ag were categorized as a severe class (71.4%), and most of the negative H. pylori Ag were categorized as a mild class (48.1%). Moreover, none of the demographical or laboratory data recorded significant values (p-value <0.05). A higher percentage of ulcerative colitis patients have H. pylori-positive test. The severity of the disease increases with age and the severe course of the disease is usually associated with the male gender rather than females.