We conducted a large-scale retrospective study to compare the surgical efficacy, practical utility, safety, and cost-effectiveness of ultrasonic harmonic scalpel tonsillectomy, hot electrocautery, and cold surgical dissection. We based our findings on the length of operating time, complication rates, the length of hospital stay for patients with complications, and relative costs. We then compared our findings with those published in earlier reports, none of which were based on a three-way comparison. Our study population was made up of 316 patients''175 males and 141 females aged 1 to 23 years (mean: 7.3)''who had undergone adenotonsillectomy or tonsillectomy alone at our tertiary care children's hospital between Sept. 1, 2000, and Aug. 31, 2001. The harmonic scalpel was used on 75 patients (23.7%), electrocautery on 109 patients (34.5%), and cold surgical dissection on 132 (41.8%). The mean length of operating time for adenotonsillectomy was 42.4 (n = 70), 43.0 (n = 103), and 49.2 (n = 95) minutes, respectively; the corresponding times for tonsillectomy alone were 23.6 (n = 5), 30.2 (n = 6), and 35.3 (n = 37) minutes. Overall complication rates were 2.7, 5.5, and 6.1%, respectively. Hospital stays for immediate (<24 hr) postoperative bleeding averaged 2.0, 1.0, and 0.7 days, respectively, and stays for dehydration averaged 1.0, 1.3, and 1.5 days. Mean per-patient institutional costs were $460.00, $310.75, and $300.00, respectively. We conclude that harmonic scalpel tonsillectomy is efficacious, practical, safe, and cost-effective, and we recommend that any institution involved with a significant number of pediatric tonsillectomies consider using it.