Concomitant fibromyalgia syndrome (FMS) has been known to be more frequent in patients with several rheumatic diseases. In this study, our aim was to investigate the prevalence of FMS in patients with familial Mediterranean fever (FMF), to analyze the possible factors related to this frequency, and to evaluate the impact of FMS on the functionality and quality of life (QoL) of the patients with FMF. One hundred cases with FMF and 100 controls were included to this case-control study. FMS coincidence was investigated in all participants according to revised 2016 classification criteria. Demographic features, FMF disease duration, FMF gene mutations, drugs used, attack frequency per year, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and serum fibrinogen levels were recorded. FMF disease severity was assessed by International Severity Scoring System for Familial Mediterranean Fever (ISSF). For the assessments of QoL and functioning, FMF-QoL, Short form 36 (SF-36), and Health Assessment Questionnaire-Disability Index (HAQ-DI) were used, and for the assessment of FMS impact, the fibromyalgia impact questionnaire (FIQ) were used. We found an FMS frequency of 33% in patients with FMF in our study using the current FMS classification criteria. This result was significantly higher than in age- and gender-similar controls (6% FMS frequency; P < 0.05). The number of woman patients and FMF disease duration were significantly higher in patients with FMF + FMS than in patients with only FMF (P < 0.001). There was no significant difference in ISSF scores, ESR, CRP, and fibrinogen levels, management regimens, and FMF gene mutation distributions between FMF + FMS and FMF groups. FMF attack frequency was reported as significantly higher in FMF + FMS patients than in others (P < 0.000). In spite of similar FMF-QoL scores, there were significant differences in HAQ-DI and SF-36 scores between groups (P < 0.05). Higher impact of FMS presented negative correlation with functioning and general health, and positive correlation with QoL in FMF + FMS (P < 0.05). Concomitant FMS was a common clinical problem in patients with FMF regardless of the severity and characteristics of FMF. The FMS impact may affect function and QoL in patients of FMF. Considerations of the FMS component in the management of FMF may contribute to the holistic approach to FMF.