The effect of oncological surgery of the head and neck area without lymph node dissection on the patency and blood flow of the internal jugular veins (IJV) was assessed in a prospective study. Ten IJV of 8 patients who underwent surgery between September 1994 and February 1997 were evaluated. Ultrasound Doppler (UD) of both IJV was performed before and after surgery. Mean age of patients was 56.3 years (range, 38 to 72 years), and all but one were men. There was no case of postoperative thrombosis. No significant differences were found between the preoperative and postoperative measurements. Consequently, oncological surgery of the head and neck area without lymph node dissection did not seem to affect the patency and UD characteristics of the IJV.