OBJECTIVES:   Fibromyalgia (FM), a chronic disorder characterized by persistent, widespread pain, has a major impact on health-related quality of life (HRQoL). However, little is known about the impact of FM severity on HRQoL in a European population.  This cross-sectional, observational study evaluated the impact of FM severity on HRQoL among French subjects. METHODS: A cross-sectional study recruited 88 FM subjects during routine visits to community-based physicians in France.  Subjects described their pain and HRQoL using the Brief Pain Inventory (BPI), Fibromyalgia Impact Questionnaire (FIQ), EuroQol- 5 questionnaire (EQ-5D), Hospital Anxiety and Depression Scale (HADS), and the Medical Outcomes Study (MOS) Sleep Scale.  FM severity was defined using subjects’ FIQ total scores: 0 - <39 (mild), 39 - <59 (moderate), and 59 - 100 (severe).  Site staff completed case report forms using subjects’ medical records. Impact of FM severity on HRQoL was investigated using analysis of variance models. RESULTS: The mean age (SD) of subjects was 55.2 (11.8) years, and 84% were female.  The mean (SD) FIQ total score was 54.8 (17.3), with most patients reporting moderate (38%) or severe (43%) FM. Subjects demonstrated poor HRQoL scores, which worsened as FM severity worsened. The mean values (SD) by FM severity (mild, moderate, severe) were 0.65 (0.18), 0.44 (0.27) and 0.18 (0.33) for the EQ-5D; 8.00 (4.08), 9.94 (2.89), and 11.92 (4.42) for HADS anxiety; and 4.71 (3.04), 6.58 (3.33), and 10.53 (4.02) for HADS depression (p<0.0001 for all comparisons). A significant association with FM severity was found for the MOS Sleep Problems Index (p=0.003), BPI Pain Intensity (p<0.0001), BPI Pain Severity Index (p<0.0001), and BPI Pain Interference Index (p<0.0001). CONCLUSIONS: FM had a substantial negative impact on HRQoL, which increased as FM severity worsened. These data allow for more precise understanding and quantification of mild, moderate, and severe FM health states.