The aim of this study was to determine if preoperative propranolol therapy has a deleterious effect on postoperative variables in patients with tetralogy of Fallot. Data from 97 patients who underwent complete repair of tetralogy of Fallot were reviewed. The patients were divided into 2 groups: those receiving preoperative propranolol therapy (n = 32) and those not receiving therapy (n = 65). Preoperative and intraoperative variables did not differ between groups. There were no differences in postoperative inotrope scores on arrival to the intensive care unit and through the first 12 hours postoperatively. There was a trend toward increased inotrope scores at 24 hours (median 8 vs 5, p = 0.05) and 48 hours (median 8 vs 3, p = 0.05) postoperatively in the patients treated with propranolol. Temporary pacing in the early postoperative period occurred more often in the propranolol group (16% vs 3%, p = 0.04). There was no difference between groups in length of mechanical ventilation, intensive care unit stay, or total hospital postoperative stay. In conclusion, propranolol therapy can be used in patients with tetralogy of Fallot until the time of surgery, without important effects on their postoperative courses. Any blunting of inotropic or chronotropic activity in propranolol-treated patients appears to be easily overcome with increased inotropic medications or temporary pacing, without increased morbidity or mortality.