Background: The postoperative thyroid bed granuloma incidence is high and it is an adittional difficulty for the ultrasound differential diagnosis of eventual local cancer recurrence. The ultrasonic knife utilization eventually can reduce the incidence of these granuloma when is compare with other traditional ligatures methods. Objective: to evaluate the postoperative thyroid bed granuloma incidence with the ultrasonic knife utilization, detected by ultrasound. Methods: retrospective study of 57 evaluable thyroidectomy performed for cancer between March and September 2010. In 46 patients were used traditional ligatures (silk or linen) and in 11, ultrasonic knife. Results: of the 57 patient included, 47 were females. The age average was 44 years old. Postoperative thyroid bed granuloma incidence was 36.3% (CI95%, 7.9%-64.7%) in the group where ultrasonic knife was used and 36.9% (IC95%, 23.0%-50.9%) in which …