We investigated the effect of levamisole on pancreatic infection in a model of acute pancreatitis (AP) in cats. Animals with and without AP received Escherichia coli intravenously. Blood was then taken at intervals for culture. AP reduced phagocytic function by 28% as measured by the rate of bacterial disappearance from the blood (p less than 0.03). In other cats, AP was induced, and E. coli were placed into the pancreatic duct. Levamisole was given orally in some cats; the remainder were untreated. Control cats (neither AP nor levamisole) also received E. coli. Seven days later, pancreases from all control cats were sterile. In AP cats, the pancreatic infection rate was 73%. Levamisole reduced the rate of infection to 22% (p less than 0.03). We concluded that phagocytic function was impaired in cats with AP. Levamisole reduced the rate of pancreatic infection.