The objective of this study was to assess internal jugular vein performance after functional neck dissection in routine and extended head and neck surgical procedures, including bilateral neck dissections, treatment of radiation failures, and those combined with microvascular free grafts. Because the indications for functional neck dissection in our practice have increased. It is important to assess the use of the procedure in these circumstances. Although previous work has suggested the patency of the internal jugular vein after functional neck dissection, actual flow rates have not been investigated. The function of the dissected internal jugular vein was analyzed with duplex ultrasound at least 4 weeks after treatment. Maximal venous flow rates were evaluated. The results of this study will be presented and discussed.