Changes in cardiac size, as measured by teleroentgenogram, in the course of essential hypertension were studied in 45 patients. Although the majority showed progressive cardiac enlargement from the discovery of hypertension, a goodly number revealed a stationary cardiac size for 10 or more years. Congestive heart failure was found to occur with normal heart measurements. Weight loss did not affect a reduction in cardiac size. Normal cardiac measurements for a decade or more were not unusual. Marked cardiac enlargement was present in several patients for 10 years with little functional limitation. Prognosis on the basis of cardiac size alone was unwarranted.