Mycoplasma synoviae (MS) was isolated from the brains of 22-week-old commercial meat turkeys displaying severe synovitis and infrequent central nervous system signs. Histological examination of the brains revealed mild-to-severe meningeal vasculitis. The vasculitis ranged from fibrinoid necrosis with little inflammation to a marked infiltration of lymphocytes and plasma cells disrupting the architecture of the vessel wall, accumulating as perivascular cuffs, and involving surrounding meninges. Occasional arteries were undergoing thrombosis. Similar lesions were occasionally seen in renal, synovial, and splenic vessels. MS isolates from the brain, trachea, and joint showed similar protein-banding patterns by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, the protein profile differed markedly from the standard MS reference strain, WVU 1853. This is the first known field case of MS isolation from the brains of turkeys.