Medicinal plants and their active constituents are traditionally used for herbal preparations and were proposed for their interesting antioxidant activities. Nearly all the medicinal plants are used for the therapeutic action and some of them are used in the investigation. Inflammation of pancreas of the exocrine part is called as acute pancreatitis. Inflammatory mediators and oxidative mediators are major factors for development of acute pancreatitis (AP). In the present study the protective effects of lawsone, myrcene, limonene, "-pinene and the underlying mechanisms in an experimental pancreatitis model. AP was induced in eleven groups of rats (n =6) by Larginine (2x2.5 g/kg, intraperitoneal, 1 h apart) and 1 h later, they received a single oral dose of lawsone, myrcene, limonene, "- pinene, (100 and 200 mg/kg) respectively, vehicle (3% Tween 80) and methylprednisolone (30 mg/kg). A saline (0.9% NaCl) treated group served as a normal control. The efficacy was determined at 24 h by determination of serum levels of amylase, lipase and proinflammatory cytokines [tumor necrosis factor (TNF)-a, C-reactive proteins and interleukin (IL)], nitrate/nitrite levels, and the wet weight/body weight ratio. Lawsone, myrcene, limonene, "-pinene and methylprednisolone treatments significantly (P < 0.05) attenuated the L-arginine induced increases in pancreatic wet weight/body weight ratio, decreased the serum levels of amylase and lipase, TNF-a, IL-6 and significantly lowered pancreatic levels of TBARS, and nitrate/nitrite. The histoimmunological findings further proved the amelioration of pancreatic injury by lawsone, myrcene, limonene and "-pinene. Hence it proved anti-inflammatory and antioxidant agent property of lawsone, myrcene, limonene and "-pinene.