Vascular diseases of CNS are usually a result of certain risk factors. In a number of cases vascular diseases are caused by inflammatory process within arteries. Establishing the intrathecal synthesis of immunoglobulins is an important indicator of the inflammatory process in the CNS. 16 patients with multifocal vascular lesions in neuroimaging examinations (MRI or CT), were analysed for the frequency of occurrence of inflammatory process within the CNS. The presence of intrathecal synthesis of IgG was established by mathematical formulas and presence oligoclonal IgG bands. In some patients presence of oligoclonal IgG bands was found, and regarded responsible for stroke. In this group the patients were younger, and mainly without other risk factors for vascular diseases. In the majority they were patients with systemic inflammatory process (e.g. SLE). The establishing of inflammatory process within the CNS sometimes has therapeutic implications.