Nimodipine, a new calcium channel blocker, seems to be effective in the treatment of vasospasm in cerebral vasculature. Typical cardiovascular side effects have limited the dose in neurology and neurosurgery to 0.03 mg/kg X h. This study was designed to examine the influence of an infusion of high dose nimodipine (0.09 mg/kg X h) on haemodynamics. 52 patients undergoing aorto-coronary bypass surgery and prospectively randomised in a nimodipine group and a control group having received 0.9% saline solution as placebo were investigated at 3 different times: 1. before induction of anaesthesia (n = 6) 2. during anaesthesia (n = 10) 3. during extracorporeal circulation (ECC n = 10). Predominant effect of high-dose nimodipine was a decrease in total systemic resistance (TSR), followed by a decrease in mean arterial pressure (MAP) and a significant increase in cardiac output. Haemodynamic effects were much more pronounced during anaesthesia in comparison to patients before induction of anaesthesia, thus demonstrating an interaction between anaesthetics and calcium channel blocker. Heart rate (HR -9.3%) and dp/dtmax (-17%) showed a decrease, too. The decrease in MAP and HR in connection with a decrease in left ventricular pressure (-21.9%) and left ventricular end diastolic pressure (-42.8%) indicate a reduction in myocardial oxygen demand. An increasing dosage of nimodipine is accompanied by increasing cardiovascular effects. From the haemodynamic point of view high dosage of nimodipine seems to be of advantage in patients with hypertension and/or coronary heart disease suffering simultaneously from cerebral vasospasm.