BACKGROUND: Inflammatory bowel disease (IBD) is an important health problem. The most important hypotheses for the pathogenesis of this disease are the deterioration of immune responses and loss of tolerance against bacteria in the enteric flora. Although IBD has been widely investigated, its treatment remains difficult. This study aims to investigate the effects of garlic oil (GO) on an experimental colitis model.,METHODS: Twenty-eight rats were randomly divided into four equal groups as follows: group 1 (sham), group 2 (control), group 3 (topical treatment) and group 4 (topical and systemic treatment). An acetic acid-induced colitis model was produced in groups 2, 3 and 4 and was administered normal saline, topical GO and topical and systemic GO, respectively.,RESULTS: Hydroxyproline levels were lower in the treatment groups than in the control group. TNF-alpha levels were significantly lower in group 3 than in group 2. Macroscopic scores were significantly lower in group 4 than in group 2. Significant differences were observed between the treatment and control groups according to their epithelial loss.,CONCLUSION: GO can reduce colonic damage and inflammation in the acetic acid-induced colitis model, with effects on both local and systemic treatments, but with a more pronounced effect in local treatment.