The third American edition has been completely revised and expanded, although parts of the text of the second edition have been included. I wish to acknowledge once again the excellent translation of the former two editions by Dr. ALAN B. ROTHBALLER and the late Dr. JERZY OLSZEWSKI. With this edition I have followed the general theme of the original German edition published in 1951. However, I have tried to consider modern techniques and the many new publications on the subject of brain tumors. Meanwhile, an early desire of mine has been fulfilled by the completion and publication of a classification which can be understood worldwide and hopefully be used widely, namely, the classi­ fication of the World Health Organization: Histological Typing of Tu­ mours of the Central Nervous System (1979). The classification which I used in the 1951 edition is very close to the final pattern of that accepted by the World Health Organization (WHO), since both follow the line of the BAILEY and CUSHING classifica­ tion of 1926/1930. To consolidate our old concepts and experiences we have reclassi­ fied our collection of 9000 cases with the assistance of my co-workers Dr. M. FUKUI, Dr. A. SATO. Dr. E. SCHARRER, Dr. E. SIMON, and Dr. J. SZYMAS. In the last decade two large atlases have been published, one called an Atlas of the Histology of Brain Tumors 1 (in six languages) and a second one called an Atlas of the Gross Neurosurgical Pathology 2.