The activity of glutamic-oxalacetic transaminase was studied in the serum of patients suffering from cholelithiasis. Patients were divided into chronic sufferers with jaundice complication and those without jaundice; a similar subdivision was made for patients with acute cholecystitis. The data showed an increase in the frequency of the alteration in enzyme activity in patients suffering from acute forms, probably as a result of the greater incidence of jaundice than is the case with chronic cholelithiasis.