Objetives: This study was conceived to study the hemodynamic pattern during methylene blue (MB) treatment on taurocholate - enterokinase induced acute pancreatitis (AP) in pigs and whether MB oxide nitric blockage influence on lipoperoxidation and histopathological findings. Methods: Thirty anesthetized Dalland pigs were divided in five groups: 1) control group (n=6); 2) MB group (n=6); 3) AP group (n=6); 4) MB previous AP (n=6) and; 5) MB after 90 minutes of induced AP group (n=6). MB was given in a bolus dose of 2mg.kg-1 iv followed by a maintenance dose of 2 mg.kg-1.h-1 iv. Hemodynamic parameters including mixed venous oxygen saturation were recorded continuously during 180 min by a Swan-Ganz catheter and a cardiac monitor. Blood samples were taken every 60 min to determine arterial and venous nitrate, malondialdehyde (MDA) , amilase and blood gases. At the end of the experiment the pancreas was removed for histopathological study. Results: Mean arterial blood pressure and cardiac output decreased over time in AP group. In the MB previous induced-AP group, there was a 70 minutes delay in the beginning of the mean decrease of the mean arterial blood pressure and cardiac output. In MB group arterial and venous nitrite decreased over time. MB infusion increased serum MDA when associated to AP. After induced AP, MB blue did not reversed the mean blood pressure and cardiac output decrease. There was no change in the serum hyperamilasemia and necrohemorragic findings with MB treatment. Conclusion: MB given prior but not after induced AP improves hemodynamic shock although it increases lipoperoxidation. Neither hyperamilasemia or hystopathological findings changed with MB treatment in taurocholate-enterokinase induced AP in pigs.