BACKGROUND: Thoracic outlet syndrome (TOS) is caused by compression of the neurovascular bundle at the thoracic outlet which often poses a diagnostic challenge. Patient management is often based on surgeon choice and experience. This study aims to describe practices relating to the diagnosis and management of TOS in the UK over a 1-year period. METHODS: This multicenter retrospective UK study included data from 16 vascular centers, analyzing surgical management and postoperative outcomes of patients treated for TOS in 2019. Outcomes were evaluated by TOS type: neurogenic (nTOS), venous (vTOS), or arterial TOS (aTOS). RESULTS: Data on 133 patients from 16 units were collected over a 1-year period. Most patients were female (87 of 133; 65%). Surgeries addressed nTOS (53 of 133; 40%), vTOS (48 of 133; 36%), and aTOS (32 of 133; 24%), with TOS type unspecified in 2 patients. Five imaging modalities were used for diagnosis. Surgical approaches included supraclavicular (90 of 133; 68%), transaxillary (23 of 133; 17%), infraclavicular (13 of 133; 10%), paraclavicular (6 of 133; 5%), and thoracoscopic (1 of 133; <1%). Pleural injury was the most reported complication (16 of 133; 12%). Most patients with pleural injury were managed conservatively, with only one-quarter requiring the insertion of a chest drain (4 of 16; 25%). Most patients (119 of 133; 89%) had symptom resolution, lower in nTOS compared to arterial and vTOS (P < 0.05). CONCLUSION: There is considerable variability in the diagnosis and management of patients with TOS across vascular centers in the UK. This study supports the development of a national registry and the creation of best practice guidelines in the future.