Egas Moniz (2), in 1927, introduced a specialized roentgen technic whereby it is possible, with the aid of certain radioopaque substances injected into the vascular supply of the brain, to visualize normal and abnormal cerebral vessels. The illustrations of his monograph, covering a wide variety of pathological conditions, can be duplicated with a relatively simple procedure now used in our department. The purpose of this communication is to present briefly this simple technic. Robb and Steinberg (14), in 1939, and Stewart, Breimer, and Maier, in 1941 (16), reported the successful use of diodrast to demonstrate the chambers of the heart and the pulmonary circulation. Gross (5, 6), after experience with cerebral arteriography in dogs, expressed a preference for a 50 per cent solution of diodrast rather than colloidal thorium dioxide, or thorotrast, which Egas Moniz believed most suitable of the available radio-opaque substances. Eisenstein and Taylor (3), who reported a case of porencephalic cyst with arte...