Familial Mediterranean fever (FMF) is characterized by recurrent short-lived/self-limiting inflammatory attacks. Besides these, a substantial number of patients with FMF present with a variety of other inflammatory diseases; however, this issue has not been systematically studied previously. Hence, we aimed to investigate the frequency of inflammatory comorbid diseases in a large FMF cohort. All patients were recruited from "FMF in Central Anatolia (FiCA) Cohort", comprising 971 (mean age 35.3 +/- 12 years, 61.5% female) adult subjects. All patients fulfilled Tel Hashomer criteria. Demographic data, FMF disease characteristics, MEFV gene mutations, and comorbid inflammatory diseases were meticulously questioned, and laboratory features and genotype data were retrieved from hospital records. There were comorbid inflammatory diseases in 205 (21.1%) patients. The most common inflammatory disease was spondyloarthritis (12.9%). Other remarkable inflammatory disorders were psoriasis, immunoglobulin A vasculitis/Henoch-Schonlein purpura, Behcet's disease and inflammatory bowel diseases. Cryptogenic organizing pneumonia is a newly defined entity in our cohort which is seemed to be associated with FMF (0.3%). Number of patients with persistent inflammation was higher in those with comorbid diseases (p < 0.001). Our results suggest that FMF is commonly associated with other inflammatory diseases. Therefore, clinicians should be cautious about comorbid inflammatory diseases in FMF patients, particularly in those with persistent inflammation. Identification of pathogenic pathways linking FMF to these diseases warrants further investigations.