alpha-Amylase isozymes were separated by electrophoresis in cellulose acetate to detect the isoforms of the chromogenic substrate manufactured by Lachema, Czechoslovakia. In a group of 20 normal subjects aged 25 to 45, alpha-amylase pancreatic isozyme activity prevailed. Patients with acute myocardial infarction developed, during 36 hours after the onset of the anginal attack, a reduction in the ratio of pancreatic amylase/salivary amylase activities in both increased and normal total alpha-amylase activities. The suggested modified technique of electrophoretic separation of alpha-amylase isozymes may become an effective method for differential diagnosis. Use of this method will help locate the source of hyperamylasemia in various diseases and will thus specify the diagnosis, ruling out the useless therapy for pancreatitis.