We report on a patient who suffered from borreliosis-induced severe cerebral vasculitis accompanied by multiple cerebral infarctions leading to hemiparesis, hemianopsia and reduced consciousness. Despite antibiotic and immunosuppressive therapy with ceftriaxon and prednisolone the patients condition deteriorated. Cerebral angiography showed multiple stenoses of large arteries of the posterior circulation and ubiquitous irregularities of small vessel wails. General reduced perfusion reflected an increased peripheral resistance. After 4 weeks of additional immunosuppressive treatment with cyclophosphamide the neurological status and angiographic findings improved dramatically.