The biochemical and histopathological changes of L-arginine experimentally induced acute pancreatitis (AP) in male rats were studied. Forty rats were separated into two groups (20 rats each). control: rats were fed normal diet. Acute pancreatitis group (AP): AP was induced by injecting 300 mg/kg bwt of L -Arginine (Arg) intraperitoneally. Blood samples were collected after 6, 24 and 96 hours and 7 days. The separated serum samples were directly used for the estimation of amylase, lipase, ALT and AST activities besides glucose levels. Also, TNF-α, IL-6, NO, total cholesterol, triglyceride, urea and creatinine levels were determined. The results revealed substantial increases in serum amylase, lipase, ALT and AST values as well as TNF-α, IL-6. NO, serum urea and creatinine levels. Meanwhile, non-significant changes in plasma, glucose and serum triglycerides levels were observed, while cholesterol showed non-significant decreased specially at 6 and 24hrs and significant elevation at 96hr. post-induction of AP. Histopathological changes of Larginine treated group showed, focal degeneration and necrosis of the pancreatic acini at 24 hours post-induction of AP, while at 7 th day focal area of acinar epithelium regenerations was recorded.