Increased alanine and aspartate aminotransferase (ALT and AST) serum levels are usually considered expressions of cellular necrosis, especially in hepatocytes. They represent cellular damage due to burn which, according to many authors, becomes normal before discharge of patients. We studied 43 consecutive burned patients, both during and after recovery, from a minimum of 120 to a maximum of 640 days, and an average of 18.62 blood samples were taken from each patient. Hepatitis A and B markers were tested. Results showed a 67.44% increase in aminotransferases in patients during recovery and a 25.58% increase after discharge. No neopositivity was observed for hepatitis A and B markers. We therefore conclude that the increase of enzymes during recovery expresses a toxic-infective phase and this increase, contrary to what was believed, does not always drop to normal values at time of discharge. Instead, after discharge, higher values can be a manifestation of a Non-A Non-B hepatitis.