Diltiazem was administered by two different dosages with 200 ug/kg 1V+10 ug/kg/min infusion, 400 ug/kg 1V+20 ug/kg/min infusion, in order to assess the interaction between sevoflurane and diltiazem on the cardiovascular function and oxygenation in dogs during inhalation of 1.0 MAC of sevoflurane. Significant decrease in heart rates, mean arterial pressure, pulmonary vascular resistance, systemic vascular resistance, coronary perfusion pressure were observed. Subsequently rate pressure product, as a parameter of myocardial oxygen consumption, decreased with no significant changes of oxygen extraction ration in 1.0 MAC of sevoflurane anesthesia with the above dosages of diltiazem in dogs. The author concludes that concomittent use of diltiazem in clinical doses induced tolerable hemodynamic depression and no untoward effects on oxygenation during maintenance of anesthesia with 1 MAC of sevoflurane. These combination would be safe for anesthetic cares in patient with ischemic heart diseases and coronary arterial diseases in which adequate oxygen supply in the heart is essentially necessary.