OBJECTIVES: This part of DEFI study aimed at assessing Qol in a FM population whose diagnosis was suspected or clinically confirmed. METHODS: In a French cross-sectional study, 6000 subjects were screened by phone using the French validated London Fibromyalgia Epidemiological study Screening Questionnaire (LFES-SQ) which was positive for 232 of them (LFES-SQ+). On this population 145 accepted to fill in SF36 and were proposed a rheumatologist consultation : 49 refused but filled in questionnaires, 20/96 who accepted the consultation and questionnaires (CS+) were diagnosed as FM (FM+) on the ACR criteria. RESULTS: Normalized SF36 subscales mean values of LFES-SQ+ subjects are as follow:  Physical Functioning (PF) 42.3 ± 10.4, Role Physical (RP) 36,8 ± 9.4, Bodily Pain (BP) 42,5 ± 7.1, General Health (GH) 39,9 ± 9.6, Vitality (VT) 41.3 ±6.6, Social Functioning (SF) 43.5 ± 9,4, Role Emotional (RE) 43,7 ± 9,4 , Mental Health (MH) 36,8 ± 7.4. Physical component score (PCS) was 42.4 ± 8.4 while mental component score (MCS) was 40.0 ± 9.5. No significant differences were observed between CS+ and CS- subjects. In contrast, comparisons between the FM+ and FM- subjects showed in most cases significant differences : PF 37.7 ± 8.1 vs 44.6 ± 9.4  (p=0.003), RP 33.6 ± 5.4   vs 36.9 ± 10.0  (p=0.053), BP 39.6 ± 6.0 vs 43.5 ± 6.1 (p=0.011), GH 33.2 ± 8.2 vs 42.3 ± 9.0  (p<0.0001), VT 39.2 ± 4.2  vs 44.7 ± 6.3 (p<0.0001), SF 39.0 ± 8.3 vs 45.8 ± 9.3 (p=0.004), RE 33.2 ± 11.3 vs 44.9 ±14.1 (p=0.027), MH 33.5 ± 5.2 vs 37.6 ± 7.2  (p=0.019), PCS 38.2 ± 7.0 vs 43.6 ± 7.8, (p=0.006), MCS 35.3 ± 7.5 vs 41.6 ± 9.4 (p=0.008). CONCLUSIONS: This study demonstrated the alterations of SF36 in positive screened and ACR criteria confirmed FM subjects.