Familial Mediterranean fever (FMF) is a rare genetic autosomal recessive disease typical for special ethnic groups, such as Arabs, Greeks, Armenians, Jews, Turks and other ethnicities inhabiting the Mediterranean coast. The characteristic clinical signs and symptoms of the disease are recurrent episodes of fever, associated with polyserositis, in particular, with benign (aseptic) peritonitis. The disease is caused by mutation in the MEFV gene encoding the synthesis of the protein pyrine, which leads to an uncontrolled release of pro-inflammatory cytokines by granulocytes. The criterion for the severe course of the disease is AA-renal amyloidosis associated with an unfavorable prognosis.Here we present a clinical case of classic FMF with high fever and abdominal pain syndrome. A 26-year-old Armenian patient had a sudden attack of fever and severe pain in the right iliac area several months before his first hospital admission. Non-steroid anti-inflammatory drugs and antispasmodics were unable to relieve the symptoms, with the attack ceasing spontaneously after 3 days from the beginning. Thereafter, the attacks recurred 1 to 2 times per month within a year. During hospital stay at the peak of the attack, peritoneal symptoms at abdominal palpation, together with neutrophilic leukocytosis and a significant increase in acute phase parameters of inflammation (C-reactive protein, fibrinogen, erythrocyte sedimentation rate) were found. Based on the characteristics of the complaints, past history, laboratory and instrumental results, we excluded infections, autoimmune and surgical disorders and made a decision to perform genetic testing to detect the MEFV gene mutation. Confirmation of the mutation has led to the definitive diagnosis of FMF. This clinical case is remarkable for its late onset, which is not typical for FMF. As a result, the patient was prescribed continuous therapy with сolchicine. Six months of the follow up have demonstrated a positive trend with no attacks during this period.