One hundred and thirteen patients with primary fibromyalgia syndrome, 77 with rheumatoid arthritis (RA) and 67 healthy controls without significant aches or pains were studied by protocol to determine clinical features of primary fibromyalgia syndrome and to assess the possible association of primary fibromyalgia syndrome with common functional disorders compared with the control groups. Previously reported common features of primary fibromyalgia syndrome are confirmed in this controlled study. In addition the extent of cutaneous hyperemia on palpation was found to be greater in patients with primary fibromyalgia syndrome than in normal controls. All the 3 functional syndromes evaluated, e.g., irritable bowel, chronic functional headache and primary dysmenorrhea, were significantly (p less than 0.005) more common in primary fibromyalgia syndrome, compared with RA and normal control groups. These data suggest that primary fibromyalgia syndrome is a characteristic clinical condition that overlaps with other well recognized functional syndromes.