| Background: Ulcerative colitis (UC), a chronic inflammatory condition of the colon with no definitive cure, necessitates the exploration of innovative therapies. Herbal remedies combined with conventional drugs may offer complementary benefits, enhancing treatment outcomes. Objectives: This study investigates the therapeutic effects of Heracleum lasiopetalum Boiss in a rat model of acetic acid-induced UC. Methods: Forty-eight adult female Wistar rats were randomly allocated to six groups (n = 8 per group) for each of two experiments. UC was induced by intracolonic administration of 1 ml of 4% acetic acid for 10 minutes. In the treatment groups, female rats received an oral gavage of 5%, 10%, and 40% aqueous plant extract, sulfasalazine (100 mg/kg), and distilled water for 6 days, starting 3 days after acetic acid administration. The protective groups received substances via oral gavage from 7 days before to 3 days after acetic acid administration. The extent of mucosal ulcers, hyperemia, inflammation, and mucosal bleeding was evaluated based on the Gerald Classification System Score (Macroscopic). Pathological assessment was conducted on prepared slides using the modified Wallace method (Microscopic). Changes in body and colon weight, along with food and water intake, were examined. Results: Significant changes in |