The effects of enflurane and halothane anesthesia on systolic time intervals were studied in 12 healthy patients. Cardiovascular measurements were made at equipotent levels of anesthesia: enflurane 1.23% end tidal and halothane 0.65% end tidal. These agents were studied first with 50% N2O and then without N2O. Systolic, diastolic, and mean arterial blood pressure were decreased more by enflurane than by halothane (p<0.05). However, halothane caused significantly more myocardial depression than enflurane, as indicated by a larger preejection period (PEP) and preejection period/left ventricular ejection time (PEP/LVET) and a smaller 1/PEP2 and ejection fraction. When N2O was discontinued, both agents increased PEP and PEP/LVET and decreased 1/PEP2 and the ejection fraction.