INTRODUCTION Thoracic outlet syndrome (TOS) includes a group of disorders caused by extrinsic compression of neurovascular structures between the 1st rib and clavicle. It usually presents as an enlarging neck mass, with shoulder or upper limb pain, weakness, paresthesias and impalpable radial pulse (Raynaud's phenomenon). PRESENTATION OF CASE We report a rare case of TOS caused by an infraclavicular subpectoral lipoma that, although challenging because of limited access and proximity of vital neurovascular structures, was successfully removed through a simple transaxillary incision with an excellent esthetic result. The patients is symptom-free 6 months after surgery. DISCUSSION Multiplicity of symptoms makes causes, diagnosis, and treatment of TOS controversial. Accurate diagnosis of TOS can be a substantial challenge in practice, because of a lack of physician awareness, overlapping of clinical features, and an absence of clearly defined diagnostic criteria. TOS may be associated with the presence of a benign subpectoral mass like lipomas, that seldom have an irregular distribution that involve neurovascular structures. CONCLUSION Although benign soft tissue tumors infraclavicular subpectoral lipomas may exert pressure on neurovascular surrounding structures during their progressive expansion and cause TOS. Therefore, a thorough preoperative study by radiological imaging such as MRI or neurophysiological test should always be performed in order to prevent unintentional lesions of the involved axillo-subclavicular plexus and plan correct surgical procedure.