The study includes 54 unselected coronary patients. Fifty underwent one or several aortocoronary bypass associated with left ventricular resection (3 times), mitral valve replacement (twice), aortic valve replacement (twice). Four patients underwent left ventricular resection alone. The operations were performed under analgesic anesthesia with sufentanil (SF) or fentanyl (F) with a double blind protocol. The ratio of concentrations of the two analgesics was SF/F = 1/10. Flunitrazepam induced and maintained sleep. After having reached by increments the total dose of 1.5 mg F/M2 or 0.15 mg SF/M2, droperidol was then added in small amounts of 3.75 mg/M2, alternating with the analgesic both being given as needed to maintain blood pressure between 100 and 120 mm Hg, in order to potentiate the level of analgesia reached and prevent vasoconstriction. Under this setting tachycardia (heart rate greater than 100 beats/min. and less than 120 beaths/min.) was observed before ECC in only 7.4% of cases with both analgesics and brief episodes of hypertension (mean maximum systolic blood pressure 140.7 +/- 20.3 mm Hg seen with SF exclusively). There was neither postoperative hypertension (except with 6 out of the 7 known hypertensive patients) nor low cardiac output, nor arbythmia. No patients remained in intensive care unit more than 24 hour. No difference attribuable to the used analgesic was detectable in the early and late follow-up in both series. On an average, the patients were discharged on postoperative day 10 in a valid condition.