Brain, heart, liver, kidney, spleen, lungs, rumen, abomasum, small intestine, skeletal muscle, and urinary bladder from healthy cattle were analyzed for creatine kinase isoenzymes as a possible aid in the diagnosis of myocardial disease. Creatine kinase was detected in all organs evaluated. In addition, 6 different fluorescing bands were detected by isoenzyme analysis. Large quantities of the same isoenzymes were in cardiac and skeletal muscle, but not in other organs. Creatine kinase isoenzyme analysis does not necessarily indicate cardiac damage, but may narrow the range of tissue damage possibilities to be included in the differential diagnosis.