In 23 patients with full atrioventricular block and congestive heart failure developing against the background of chronic ischaemic heart disease Isuprel was injected intravenously at a speed of 1 to 3 muG/min. A positive chronotropic effect of the drug was observed and attributed to the dose employed. Isuprel produced a positive dynamics in the structure of the cardiac cycle in the treated patients. A course of such therapy resulted in a reduction, or even disappearance of the circulatory insufficiency signs in the majority of patients, but sinus rhythm could not be restored in either of them. The noted side effects were typical of beta-stimulators. Two patients developed anginal pains in the zone of the heart when the drug was given intravenously.