Using scanning electron microscopy, possible ways of the appearance of macrophages on the epithelial surface of the cerebral vascular plexus in rats were studied. The data obtained support the theory which postulates that macrophages are formed in the blood flow or the connective tissue and that subsequently they penetrate through the epithelium of the vascular plexus onto its surface having contact of the cerebrospinal fluid. The structural stages of this process are also reflected in the presented findings.