The objective of our nonrandomised controlled study was to evaluate the effect of a 4-week aerobic exercise program on muscle performance in patients with fibromyalgia. Thirty-two women were consecutively divided into two groups, either study or control group. Study group attended at aerobic exercise program on treadmill lasting 30 minutes. five times a week for four weeks. Electrotherapy and thermotherapy also were applied to back region of patients in study group for two weeks. Control group were treated only the same electrotherapy and thermotherapy interventions lasted 30 minutes, five times a week for two weeks. All patient, were assessed before and after treatment protocols with respect to pain, fatigue, fibromyalgia-related symptoms, tender point count/score, psychological status and muscle strength of knee extensors and flexors. There were statistically significant improvements in the intensity of pain, fatigue, percentage of morning stiffness, paresthesia, irritable bowel syndrome, tender point count/score, psychological status and muscle strengths after acrobic exercise program. However, there were significant improvements only in the intensity of pain. percentage of paresthesia, tender point count/score in the control group. Submaximal aerobic walking, program increased muscle performance in addition to positive effects on pain, fatigue, fibromyalgia-related symptoms and psychological status in patients with fibromyalgia.