ObjectiveTo investigate the cause and treatment for chyle fistula after neck radical dissection using harmonic scalpel. MethodsFrom January 2005 to April 2009, 105 patients with thyroid carcinoma underwent thyroidectomy by harmonic scalpel (harmonic scalpel group) and 110 patients with thyroid carcinoma by conventional procedures (conventional group). Postoperative chyle fistula in all the cases was studied retrospectively. ResultsThe incidence of chyle fistula was 5.71% (6 of 105 patients) in the harmonic scalpel group and 0.91% (1 of 110 patients) in the conventional group. The difference was significant between two groups (Plt;0.05). ConclusionsHarmonic scalpel increases the risk of chyle fistula in neck radical dissection. The conventional procedures with exposing and preserving or ligating the thoracic duct can reduce the risk significantly.