¹Department of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of Ilorin, Ilorin, Nigeria DOI : 10.29228/jrp.171 Allium cepa bulbs (onions) are widely consumed as food, spice and for medicinal purposes. The peels of Allium cepa (A. cepa) are often discarded as waste but have been reported in literature to contain beneficial phytoconstituents with pharmacologic activity. This study was designed to evaluate the anti-inflammatory and mucosal protective activity of aqueous extract of Allium cepa peels. The anti-inflammatory activity was investigated using carrageenan-induced paw edema. Rats were treated orally with extract (200-400 mg/kg) and acetylsalicylic acid (100 mg/kg) as positive control. Thirty minutes after, carrageenan (0.1 ml of 1% w/v) was injected on the sub plantar surface of the right hind paw and edema measured with a digital vernier caliper. The mucosal protective activity was determined with acetylsalicylic acid-induced mucosa damage. The rats were pretreated orally with omeprazole (20 mg/kg) and A. cepa peel extract (200 – 400 mg/kg) before the administration of acetyl salicylic acid (300 mg/kg). The stomach of the rats was removed after three hours then examined macroscopically for bands of inflammation, color and hemorrhagic streaks. A. cepa peel extract (200 and 400 mg/kg) produced a significant (p<0.01) reduction in carrageenan-induced paw edema. The percentage inhibition of inflammation by extract (200 and 400 mg/kg) at 150 minutes post-treatment with carrageenan was 83.39 % and 82.76 % respectively, while acetylsalicylic acid (100 mg/kg) produced an inhibition of 72.41 %. The aqueous peel extract also caused significant (p<0.001) inhibition of gastric inflammation induced by acetylsalicylic acid. The percentage inhibition by A. cepa extract (200 and 400 mg/kg) was 86.04 % and 92.79 % respectively, while omeprazole (20 mg/kg) produced an inhibition of 77.48 %. The results obtained from this study show the aqueous peel extract of Allium cepa has potential anti-inflammatory and gastric mucosa protective activity. Keywords : Allium cepa; Peel; Anti-inflammatory; Gastroprotective; Acetylsalicylic acid