Histopathological study of intracerebral implantation of sarcomas, performed in rats (fibrosarcomas) and mice (sarcoma 180). The intracerebral implantation of fibrosarcoma has developed in about 45 days a well limited tumor, with little infiltration of the adjacent nervous parenchyma, never streading to longer distances because the strong cohesion between its cells, with great differentiation of reticular fibers and collagen. On the contrary, the innoculation of sarcoma 180, chiefly of the ascitical form, has rapidly lead to a strong intracranial hipertension, with dissemination of neoplastic cells through the subarachnoid and intraventricular spaces. Both neoplasies were extending through the perivascular spaces, but in different ways: the sarcoma 180 had a very strong and rapid dissemination to long distances, while the fibrosarcoma disseminated only to the vessels adjacent develloping tumor. Based on personal observations and on specialized bibliography, we concluded that the etiological agents of these tumors exerts their action on different cellular strains.