Fibromyalgia (FM) is a complex syndrome characterized by chronic widespread pain and a heightened response to pressure. Most medical researches pointed out that FM patients with endothelial dysfunction and arterial stiffness. A continuous-wave near-infrared spectroscopy (NIRS) system is used in present study to measure the hemodynamic changes elicited by breath-holding task in patients with FM. Each patient completed a questionnaire survey including demographics, characteristics of body pain, associated symptoms, headache profiles and Hospital Anxiety and Depression Scale. A total of 27 FM patients and 26 health controls were enrolled. In comparison with healthy controls, patients with FM showed lower maximal and averaged change of oxyhemoglobin concentration in both the left (1.634 ±0.890 and 0.810 ±0.525 $μ$M) and the right (1.576 ±0.897 and 0.811 ±0.601 $μ$M) prefrontal cortex than healthy controls (P <.05 for both sides) during the breath-holding task. In conclusion, FM is associated with altered cerebrovascular reactivity measured by NIRS and breath-holding task, which may reflect endothelial dysfunction or arterial stiffness. Oxygenated hemoglobin concentration changes of healthy controls and FM patients.