Twenty-four patients with severe, 24 with moderate, and 24 without heart disease were selected for measurements of systolic time intervals (STI) and blood pressure before and during anesthesia. In all patients anesthesia was induced with thiopental, 4 mg/kg. After tracheal intubation. 12 patients from each heart-disease class received halothane–N2O–O2(halothane) and 12 patients from each class morphine–d-tubocurarine–N2O–O2(MS-dTc). Thiopental increased the pre-ejection period (PEP). decreased left ventricular ejection time (LVET). and accelerated heart rate (HR). These changes were similar in patients with and without heart disease. Halothane and MS-dTc lowered systolic blood pressure and increased PEP/LVET. With halothane but not with MS-dTc these changes were more pronounced in patients who had heart disease. Changes of the PEP/LVET ratio during halothane anesthesia were a better discriminating variable among patients without, with moderate, and with severe heart disease than were changes in systolic blood pressure.