A group of 48 patients (42 suffering from hepato-biliary diseases and 6 without hepatic diseases) was followed by the authors for a period lasting from 5 to 8 years, 13 out of them for longer. The hepatic disease was assessed on the basis of physical examination, current liver chemistry and proper and specific instrumental procedures. Initial and final diagnosis and the aminotransferases (AST, ALT) trend in years were carefully considered. First of all it was concluded that no advantage is obtained in monitoring the two aminotransferases instead of one alone. Moreover it is stressed the opportunity of referring aminotransferases activities in a simple way such as per cent of variation as referred to considered upper normal value differing from one to the other laboratory. The aminotransferase increase maintains an important and diagnostic significance in acute liver damage such as in acute hepatitis. An inappreciable prognostic value may be drawn from the follow up of these enzymatic parameters: for example the development of posthepatic fibrosis, or cirrhosis or hepatoma cannot be foreseen on the basis of the aminotransferases trend. A greater variability and sharp increases in AST-ALT values are recorded in patients with biliary gallstones.