In the first part of the review article authors summarize our knowledge on the role of complement in atherogenesis and the development of I/R injury as well as the complement activation products which contribute to these pathological processes. In the second part of the review authors highlight the complement dependent processes which participate at the pathomechanism of cerebrovascular diseases, the development of cerebral infarct in ischemic stroke and the restenosis which may occur a part of the patients who underwent eversion endartectomy operation. Literature data and the recently published data of the authors' group indicate that the complement system is strongly activated at the onset of the ischemic stroke and the extent of this activation is positively correlated with the bad outcome of the disease. This observation may be one of the starting points of the introduction of the complement activation-inhibiting therapy in ischemic stroke.