Familial Mediterranean fever (FMF) is a genetic autoinflammatory disorder characterized by serositis and recurrent fever. Previous reports identified patients with antineutrophil cytoplasmic antibody (ANCA)-positive FMF, but vasculitis symptoms were not reported.We report the case of a 44-year-old man with numbness. He had a history of 3 episodes of pleurisy and was being treated with propylthiouracil for hyperthyroidism. Because he was ANCA-positive, we suspected drug-induced ANCA-associated vasculitis and propylthiouracil was discontinued. However, his numbness was not ameliorated, and he again developed high fever with pleurisy.Diagnosis of FMF was finally made, and genetic analysis revealed compound heterozygous mutations in exon 2 of the familial Mediterranean fever gene (L110P/E148Q).The patient was treated with 0.5 mg/day of colchicine.His numbness improved, and fever has not recurred.Appearance of ANCA and development of vasculitis should be considered in a clinical course of FMF with hyperthyroidism.