The aim of this study was to investigate common symptoms and divergent features in fibromyalgia (FS) and masticatory myofascial pain (MFP) in patients affected by cran iomandibular disorders. Twenty-three women with MFP and 23 women with FS were studied. All patients were examined by a dentist and by a rheumatologist. Craniomandibular disorders were assessed with a subjective symptoms questionnaire, detailed history interview, joint function examination, and manual palpation of masticatory and cervical muscles. The Middlesex Hospital Questionnaire was used to obtain personality profiles of the patients. The craniomandibular disorders questionnaire revealed various similarities in the two groups, the most striking of which were pain during mandibular function, articular noises, and headache. Both groups had muscle lpain upon palpation; the mean scores (on a 0 to 4 scale) did not differ significantly between the two groups and ranged between 1.39 (SD 1.2) and 2.86 (SD 0.75). The mean value of active mouth opening was 40.9 mm (SD 9.1) in MFP patients and 44.6 mm (SD 7.2) in FS patients, while the mean value of passive opening was 49.6 mm (SD 6.0) in MFP pati ents and 49.8 mm (SD 3.5) in FS patients. These values did not differ significantly between the two groups, bu t did differ from the normal population, similar to the trend of the psychologic profile. The authors conclude that the physician should be alert to the need to conduct interdisciplinary evaluations in the diagnosis and management of FS and of MFP.