Serial measurements of serum uric acid were performed on patients suffering from acute myocardial infarction. Nearly 80 percent of the cases demonstrated a fall in uric acid concentrations during the first two days of hospitalization and a subsequent return to initial levels within six to eight days. There was a relationship between the decrease in uric acid levels and the serum lactate dehydrogenase activity. No evidence could be found that male patients were hyperuricemic as compared to control subjects. However, female patients between 40 and 60 years of age demonstrated significantly higher uric acid levels than healthy women of corresponding ages, even after adjustment for diuretic use.