Objective: To explore the therapeutic role of morin against L-arginine-induced acute pancreatitis in rats. Methods: The group 1 received two intraperitoneal injections of normal saline, and groups 2-4 were given two intraperitoneal injections of L-arginine (250 mg/100 g body weight) at 1 h interval to induce acute pancreatitis. Subsequently, group 2 received no further treatment while groups 3 and 4 were treated with morin (30 mg/kg) and diclofenac sodium (30 mg/kg), respectively. Blood glucose and serum levels of insulin, α-amylase, malondialdehyde, myeloperoxidase, alanine aminotransferase, aspartate aminotransferase and cholesterol were measured. Moreover, histopathological study was carried out to investigate the effect of morin treatment on physiology of the pancreas. Results: L-arginine significantly altered the level of blood glucose and serum levels of insulin, α-amylase, malondialdehyde, myeloperoxidase, alanine aminotransferase, aspartate aminotransferase and cholesterol. Treatment with morin or diclofenac sodium significantly improved the levels of these biomarkers. Furthermore, morin showed more significant effect than diclofenac sodium. Histopathological analysis verified that morin protected the pancreas from deleterious effects of L-arginine. Conclusions: Morin plays a protective role against L-arginine- induced acute pancreatitis via reducing lipid peroxidation and tissue inflammation, and attenuating acute pancreatitis-associated alteration in insulin secretion and glucose metabolism.