A 23-year old female was referred to our clinic for intermittent fever occurring over a period of eight years. Every time she developed fever, blood examination revealed elevated leukocytes and C-reactive protein (CRP). Antibiotics were always given based on elevated CRP with apparent improvement. However, the pattern of periodicity with absence of symptoms in between suggested periodic fever syndrome, particularly Familial Mediterranean Fever (FMF), which was later confirmed by mutation analysis. In Japan there is a tendency to use antibiotics solely based on "elevated CRP"; however, careful review of patient history is essential to identify FMF while avoiding the use of unnecessary antibiotics.