OBJECTIVE: To investigate the protective effect of antibiotherapy in the early phase of acute pancreatitis on cellular injury induced in lungs and liver. BACKGROUND: Cellular viability and plasma nitric oxide (NO) levels were assessed to determine the efficacy of highly bactericidal imipenem and quinolones on liver and lung injury. METHODS: Imipenem, levofloxacin or saline were administered to rats with caerulein induced pancreatitis. Twenty-four hours later serum amylase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and NO levels, pancreatic interstitial inflammation, acinar cell necrosis, acinar cell vacuolisation, peripancreatic fat necrosis; spotty necrosis, focal inflammation of liver and inflammatory processes in the lungs were assessed. RESULTS: Enzyme levels in the antibiotherapy groups were lower than in the control group. Serum NO levels were higher only in the imipenem group. Levofloxacin decreased acinar cell vacuolisation in the pancreas; interstitial edema, neutrophilic infiltration and interstitial enlargement in the lungs. Antibiotherapy decreased spotty necrosis, apoptosis and focal inflammation in the liver. CONCLUSIONS: Although treatment with imipenem is associated with higher NO levels than levofloxacin, levofloxacin prevents organ injury more effectively than imipenem in acute pancreatitis. Our results indicate that antibiotherapy in the early period of necrotizing pancreatitis prevents cellular damage induced in pancreas, liver and lungs.