Background: Reoperation in the neck can be challenging and is associated with increased complication rates and operative times. Here we analyze our methylene blue dye injection method to localize reoperative neck pathology in patients with thyroid cancer and lymph node metastases. Study Design: We retrospectively reviewed the records of all patients at a single university tertiary care center who had reoperative neck surgery for recurrent thyroid cancer between 2004 and 2009, and who also underwent intraoperative methylene blue dye injection. Outcomes measured were efficacy and safety of the injection technique as well as complication rates. Results: Fifty-three operations were performed in 44 patients (average age, 51.2 years [range 16 to 83 years]). Ninety-one percent (48 of 53) of the operations resulted in successful resection of recurrent disease. Of these, 96% (46 of 48) were guided successfully by blue dye injection. Thyroglobulin became undetectable in 42% (11 of 26) of patients. Neck pathology included the following thyroid cancers: papillary (48 of 53), follicular (2 of 53), medullary (2 of 53), and tall cell variant (1 of 53). Among these patients, there were a total of 26 central and 38 lateral neck dissections. The average number of previous neck dissections was 2 (range 1 to 5). The mean intraoperative ultrasound/injection time was 21.3 min (n = 13). Median operative time was 90 minutes (range 40 to 300 minutes). Complications included 2 permanent vocal cord paralyses, 1 instance of permanent hypocalcemia, and 3 instances of temporary hypocalcemia. There were no complications related to the dye injection. Conclusions: Intraoperative, ultrasound-guided, methylene blue dye injection is a safe and effective technique. It facilitates tumor localization and removal especially in patients requiring reoperative neck surgery. © 2012 American College of Surgeons.