Fifty-two patients with mechanical neck pain were randomized to receive thoracic spine self-mobilization (n=25) or sham self-mobilization (n=27) for functional improvement. The primary outcome of interest was the level of disability, measured using the Neck Disability Index (NDI). Secondary outcomes of interest included resting neck pain on a Visual Analogue Scale (VAS), and active range of motion of the cervical spine (i.e., flexion, extension, right and left lateral cervical flexion, and right and left cervical rotation). Outcomes were assessed immediately after the performance of intervention. Results demonstrated no statistical significant differences between the two groups for improvement over time in all outcomes except range of motion in flexion and range of motion in extension, which were statistically significantly in favour of the active self-mobilization group (p=0.005; p=0.036, respectively). No adverse events were observed in either group.