The aim of this prospective randomized trial was to compare operative factors, postoperative outcomes and surgical complications of open total thyroidectomy when using the Harmonic Scalpel (HS) versus Conventional Haemostasis (CH). Methods. 100 consecutive patients underwent open total thyroidectomy were randomized into two groups: group CH (Conventional Haemostasis) and group HS (Harmonic Scalpel). We recorded the following: age, sex, pathology, thyroid volume, haemostatic technique, operative time, drainage volume, thyroid weight, postoperative pain, postoperative complications, and hospital stay. The results were analyzed using the Student's t test and χ
2 test. Results. No significant difference was found between the two groups concerning mean thyroid weight and mean hospital stay. The mean operative time was significantly shorter in the HS group. The total drainage fluid volume was lower in HS group. Two (4%) transient recurrent laryngeal nerve palsies were observed in CH group and no one (0%) in the HS group. Postoperative transient hypocalcemia occurred more frequently in the CH group. HS group experienced significantly less postoperative pain at 24 and 48 hours. Conclusions. In patients undergoing thyroidectomy, HS is a reliable and safe tool. Comparing with CH techniques, its use reduces operative times, postoperative pain, drainage volume and transient hypocalcemia.