Thirty patients who had undergone coronary artery bypass grafting and who required vasodilator therapy for control of arterial hypertension were allocated to receive either low-dose or high-dose enoximone or placebo infusions. A closed-loop arterial pressure control system was used to assess cardiovascular stability and the amount of sodium nitro-prusside required to maintain control. There were no significant differences between the three groups in the time spent at 10, 20 and 30 mm Hg below the target pressure or at 10 and 20 mm Hg above the target pressure. However, the low-dose enoximone group spent a statistically greater amount of time at 30 mm Hg above the target pressure. There were no significant differences in the amount of sodium nitroprusside required to maintain control, in the duration of sodium nitroprusside infusion or in the heart rate. In conclusion, enoximone was not associated with a clinically significant effect on systolic pressure.