The increment and time course of serum glutamic oxaloacetic transaminase (SGOT) was evaluated in 108 patients with acute cholecystitis, 26 of whom were jaundiced. Seventy-seven percent presented with an elevated SGOT. All of the jaundiced patients had an elevated SGOT and higher values were generally achieved in jaundiced than in nonjaundiced patients. However, 70% of anicteric patients also had an elevated SGOT. Serial enzyme determinations were obtained over a period of at least five days in 38 anicteric and 22 jaundiced patients who presented with elevations. Invariably, the initial SGOT value was the maximal level obtained. When compared to the increment and time course of the SGOT in patients with acute myocardial infarction or hepatocellular disease, the enzyme activity which characterizes an elevated SGOT in patients with acute cholecystitis can be of value in the differential diagnosis of these diseases.