Eighty‐eight patients with blood diseases were examined by cranial computerized axial tomography (CAT). They included 40 acute leukemias (AL), 17 Hodgkin's diseases (HD), 7 Non‐Hodgkin's lymphomas (NHL), 4 chronic leukemias (CL), 4 multiple myelomas (MM), 3 macroglobulinemias, 5 polycythemias, 3 thrombopenic purpuras and 5 various blood disorders. Among the AL, 15 p. 100 (6 cases) had parenchymal lesions that we considered as leucoblastic infiltrations (proved by histology in one patient). There was also one case with cerebral hematoma, one case with hemorrhagic encephalomalacia, two cases with toxoplasmic or iatrogenic parenchymal calcifications one case with iatrogenic cortical atrophy and one case with unaccounted parenchymal hypodense zone. Among the HD, 41 p. 100 (7 cases) had intracranial localizations (proved by histology in one patient). One patient out of 7 NHL had the same type of image. All CL cases had normal CAT. One patient with MM and another with macroglobulinemia had encephalomalacia. One patient presenting polycythemia had a sub‐dural hematoma. Finally, among the other patients there were two cases of cerebral hematoma during thrombopenic purpuras. It is suggested that CAT permits a more complete neurologic work‐up for patients with blood diseases, in conjunction with other investigations (especially CSF findings). It also permits a better knowledge of the frequency and varieties of endocranial complications in hematology, mainly in AL and lymphomas. Our preliminary findings are discussed in this article.