Fibromyalgia syndrome (FMS) is associated with chronic widespread pain and at least eleven positive tender points out of 18 according to the American College of Rheumatology (ACR) 1990 criteria. Neuromuscular electrical stimulation (NMES) stimulates nerve fibers providing innervation in healthy muscle and muscle fibers in denervated muscle to produce contraction. All patients will be taught neck normal joint motion exercises, upper trapezius stretching exercise and posture exercises. Patients included in the study will be randomly distributed equally between the two groups. In addition to the study group, NMES will be applied to the upper trapezius muscle for 30 minutes 5 days a week for 4 weeks. Pain, disability and sleep quality of all patients will be evaluated.