BACKGROUND: Optimal management of recurrent neurogenic thoracic outlet syndrome (NTOS) remains a considerable challenge. OBJECTIVE: To assess the safety and effectiveness of reoperative brachial plexus neurolysis in patients with recurrent NTOS. METHODS: From 2009 to 2019, 85 patients underwent reoperative supraclavicular brachial plexus neurolysis for recurrent NTOS after a previous anatomically complete supraclavicular decompression. Data from a prospectively maintained database were analyzed retrospectively. RESULTS: The mean patient age at reoperation was 36.9 ± 1.3 (range 15-64) years, 75% were female, and the interval after previous primary operation was 2.5 ± 0.2 years. Intervening injury had precipitated recurrent NTOS in 14 patients (16%), and the mean Disability of the Arm, Shoulder, and Hand (QuickDASH) score before reoperation was 65.2 ± 2.6, reflecting substantial disability. Operative findings consisted of dense fibrous scar tissue surrounding/encasing the brachial plexus. Compared with the previous primary operations, reoperations had a shorter operative time (198 ± 4 vs 161 ± 5 minutes, P < .01) and hospital stay (4.4 ± 0.2 vs 3.6 ± 0.1 days, P < .01), but there were no significant differences in the frequency of prolonged hospitalization (7.1% vs 4.7%), early reoperation (3.5% vs 1.2%), or 30-day hospital readmission (8.2% vs 7.1%). During a median follow-up of 4.8 years, QuickDASH scores improved by 23.3 ± 2.6 (34.2% ± 3.6%; P < .01) and patient-rated outcomes were excellent in 24%, good in 42%, fair in 26%, and poor in 8%. CONCLUSION: Reoperative supraclavicular brachial plexus neurolysis is technically challenging but safe and effective treatment for recurrent NTOS, with significant improvements in symptoms and function. Diminishing perineural scar tissue development and avoiding secondary injury would likely decrease the need for reoperations.