To determine the frequency and severity of gastrointestinal (GI) symptoms in patients with fibromyalgia (FM). We included 152 women with FM (mean age 45.4 +/- 12.2 yrs), 98 women with rheumatoid arthritis (RA; mean age 45.5 +/- 12.3 yrs), and 60 healthy female controls (mean age 44 +/- 11.3 yrs). All patients were questioned about the severity of their chronic widespread pain, symptoms of FM, symptoms of dyspepsia, using a visual analog scale (VAS), and anxiety-depression scale. Patients were asked self-reported (yes/no), symptom-based (>/= 2 criteria) constipation and severity of constipation questions, and about the severity of quality of life (QOL) disturbance secondary to dyspepsia and constipation. Patients with FM had higher symptom severities for belching, reflux, bloating, sour taste, and vomiting than patients with RA and controls (all p values < 0.01). Patients with FM had significantly more dyspepsia-related QOL disturbances than the other 2 groups (p < 0.01). FM and RA patients had more frequent self-reported constipation than controls (respectively, 42.1%, 48%, 21.7%; p < 0.01). The frequency of symptom-based constipation was significantly higher in the RA group (49%) than in FM (29.6%) and control groups (23.3%) (p < 0.01). Constipation-related QOL disturbance was significantly higher in patients with FM than in controls (p < 0.01). In patients with FM, the severity scores of dyspepsia symptoms, constipation, and dyspepsia-related QOL disturbance were higher than in patients with RA and controls. The higher GI symptom severity in patients with FM might have negative effects on their QOL.