Objective: To elucidate the ameliorative effect of hydroalcoholic extract of leaves of Hibiscus rosa sinensis (HRS) in acetic acid induced experimental colitis in male wistar rats. Methods:The animals were administered with 2 mL acetic acid (4%) via intra rectal. The animals were divided into various treatment groups (n=6). Prednisolone was used as standard drug and HRS was administered at a dose of 50, 100 and 200 mg/kg p.o. The control group of animals received 1 mL of vehicle (distilled water). Ulcer area, ulcer index, spleen weight, colon weight to length ratio, macroscopic score, haematological parameters, colonic superoxide dismutase (SOD), glutathione (GSH), myeloperoxidase (MPO), malondialdehyde (MDA), tumor necrosis factor-毩(TNF-毩), nitric oxide (NO) and histological changes were recorded after the treatment regimen of 11 days. Results: Intrarectal instillation of acetic acid caused enhanced ulcer area, ulcer index, spleen weight, colon weight to length ratio, colonic MPO, MDA, NO and TNF-毩 It caused significant decreased level of SOD and GSH. Pretreatment with HRS for 7 days exhibited significant effect in lowering of oxidative stress, colonic NO, TNF-毩 and elevation of SOD and GSH at a dose of 100 and 200 mg/kg in acetic acid induced colitis. Conclusions: The present investigation demonstrates HRS is of potent therapeutic value in the amelioration of experimental colitis in laboratory animals by inhibiting the proinflammatory mediator like NO and TNF-毩.