Denervation of sensory and sympathetic nerve fibers and reduced blood flow result in decreased bone mineral density (BMD). In this study, we aim to detect the effect of compression of brachial plexus and subclavian vessels on the forearm BMD in patients with thoraric outlet syndrome (TOS). Twenty-three patients with TOS (17 females and 6 males) were enrolled in the study. Thirty-three extremities of the patients with TOS were classified as true neurogenic (1), vascular (15) and disputed neurogenic TOS (17). Thirty upper extremities of 15 age- and sex-matched healthy subjects were evaluated as controls. Electrophysiological testings and Doppler ultrasonography were performed. Comparisons of the dominant and the non-dominant forearm BMD between patients and controls, and between the involved and the non-involved sides in TOS patients revealed no significant differences (P < 0.05). In conclusion, intermittent compression of brachial plexus and subclavian vessels in patients with disputed and vascular TOS does not seem to affect forearm BMD. Further studies are needed to detect the effect of persistent neurovascular compression in TOS.