A 60-year-old woman with a two-year history of rheumatoid arthritis (RA) developed recurrent two- to three-day attacks of fever (>38°C) accompanied by monoarthritis of the right hip joint. The first attack occurred two months after beginning anti-tumor necrosis factor-α therapy. Since a diagnosis of infectious arthritis was suspected, the therapy was discontinued. Thereafter, the patient repeated similar episodes; however, oral colchicine effectively controlled the attacks. The patient was diagnosed to have familial Mediterranean fever (FMF). The clinical manifestations of FMF mimic infectious complications during anti-RA therapy. Clinicians should therefore consider the possibility of FMF development in RA patients exhibiting recurrent febrile attacks.