The purpose of this study was to investigate the effect of dry needling on the blood flow and oxygen saturation of the trapezius muscle. Twenty healthy participants participated in this study. One single dry needling procedure was performed in the right upper trapezius, at a point located midway between the acromion edge and the seventh cervical vertebrae. Using the oxygen to see device, blood flow and oxygen saturation were evaluated at the treated point and 3 distant points (similar point in the left upper trapezius and 30 mm laterally from this midpoint). Measurements were taken at baseline and in the recovery period (0, 5, and 15 minutes posttreatment). After removal of the needle, the blood flow and oxygen saturation increased significantly from the pretreatment level in the treated point (P ≤ .001), and these values remained high throughout the 15-minute recovery period. There were only minor changes in the distant points. These results suggest that dry needling enhances the blood flow in the stimulated region of the trapezius muscle but not in a distant region used in this study.