BACKGROUND: Hemostasis is important in thyroid surgery to avoid complications. Our aim was to evaluate the effectiveness of the harmonic scalpel in patients undergoing total thyroidectomy.METHODS: In this study, 90 patients were randomized into group A (classic technique of tying and knots) and group B (harmonic scalpel). We recorded the following: age, sex, pathology, thyroid weight, hemostatic technique, duration of operation, change in calcemia (DeltaCa), change in hematocrit (DeltaHt), change in hemoglobin (DeltaHgb), change in white blood cell count (DeltaWBC), vocal motility, operative difficulty, postoperative vocal alteration, postoperative pain, complications, blood in the drains, operating time, mass of gland excised per minute, and hospitalization.RESULTS: Differences (p < .05) were observed concerning duration of surgery, operative difficulty, postoperative pain, hospitalization, DeltaWBC, and quantity of gland removed per minute. No recurrent laryngeal nerve (RLN) palsies were observed.CONCLUSIONS: Use of the Harmonic Scalpel in total thyroidectomy is more effective than the clamp-and-tie technique: the duration of surgery, intraoperative difficulty, postoperative pain, and hospitalization are reduced. Both techniques are equivalent concerning RLN injuries, postoperative vocal alterations, and blood loss.