Mean arterial pressure, cardiac output and heart rate were determined in 8 male New Zealand white rabbits while conscious and after being anesthetized with halothane plus N2O for 15 min. Delivery of the anesthetic agent was stopped and the measurements repeated at 15, 30, 60 and 210 min. In a separate experiment blood samples were obtained for plasma renin activity (PRA) in 6 rabbits before anesthesia, after 15 min of halothane plus N2O administration, and again 210 min after cessation of the anesthesia. This experiment was repeated with the same rabbits except that they were allowed to breath room air instead of the anesthesia. The halothane anesthesia resulted in decreased mean arterial pressure and cardiac output, but these returned to the preanesthetic levels by 15 min after stopping the anesthesia. Heart rate increased during halothane administration, and although it tended to return toward control levels after cessation of the halothane, heart rate was still elevated 210 min later. Halothane plus N2O produced an increase in PRA, which then subsided to normal by 210 min following anesthesia; breathing room air did not result in increases in PRA. Although short-term anesthesia with halothane plus N2O resulted in cardiovascular changes in rabbits, after cessation of the anesthetic agent the cardiovascular system quickly returned to normal.