Isolated arteritis of the central nervous system (CNS) is a relatively rare condition. Of the patients treated at our department two presented with characteristic features and eventually the diagnosis of isolated arteritis of the CNS was established. Headaches and relapsing lesions of cerebral nerves were predominant in the clinical picture of the first patient. In agreement with the clinical picture suggesting that small arteries were affected, the angiographic (AG) finding was negative and the diagnosis was based mainly on the positive effect of immunosuppressive treatment. The second patient with relapsing monofocal brain damage had a typical AG finding and a positive response to the treatment. The clinical picture of isolated arteritis of the CNS can be rather varied, with headaches and different neurological features being predominant. Both AG and bioptic examinations may prove negative. Positive response to immunosuppressive treatment is to be considered a characteristic feature of the disease. (Fig. 3, Ref. 11.)