The effectiveness of oral transmucosal fentanyl citrate (OTFC) as preanesthetic medication was compared with oral meperidine, diazepam, and atropine (MDA) in 40 pediatric patients scheduled to undergo repair of congenital heart defects. In a double-blinded manner, patients received a fentanyl lollipop (20–25 μg/kg) and a placebo oral solution (0.4 ml/kg) (n = 20) or a placebo lollipop and an oral solution (0.4 ml/kg) of meperidine (1.5 mg/kg), diazepam (0.2 mg/kg), and atropine (0.02 mg/kg) (n = 20). The patient's vital signs, systolic and diastolic blood pressures, heart rate, respiratory rate, and oxyhemoglobin saturation (Spo1), as well as activity and apprehension scores were evaluated and recorded at baseline and at 10-min intervals. The patient's emotional status at the time of parental separation and at induction of anesthesia were also assessed. Side effects and onset of action were observed. After OTFC, onset of sedation was significantly faster than with the oral solution of meperidine, diazepam, and atropine. In both groups there was no significant change in heart rate. Although systolic blood pressure, diastolic blood pressure, and respiratory rate showed statistically significant decreases, these changes were not clinically significant The child's emotional status at the time of separation from the parents and during induction was similar in both groups. Side effects with OTFC were more frequent: nose itching occurred in 65%, body itching in 10%, and vomiting in 30%. Two patients (10%) in the OTFC-treated group became hypoxemic (Spo1< 90) and required supplemental oxygen. In the group receiving oral meperidine, diazepam, and atropine, 10% had mild facial pruritus and 5% complained of a dry mouth. When compared with oral meperidine, diazepam, and atropine, OTFC in the dosage used is readily acceptable, provides more rapid sedation, but has considerably more preoperative side effects. Consequently, OTFC in the dose used in this study cannot be recommended as a preanesthetic medication for patients with congenital heart disease.