This book is a reprint, with corrections of an article published in the February, 1925, number of the American Journal of Roentgenology and Radium Therapy. The author aims to present to the medical profession, and especially to those interested in bone tumors, a classification of such tumors with a nomenclature suitable to clinicians, roentgenologists and pathologists, thereby making possible a more common understanding of bone tumors. The classification herein proposed, and one adopted jointly by the committee of registry of bone sarcoma, consisting of the author and Drs. Ewing and Bloodgood, and the committee of the Clinical Pathological Association, composed of Drs. MacCarty, Sondern, St. George and Bell, is one of eight divisions. These divisions are metastatic tumors, periosteal fibrosarcoma, osteogenic tumors (benign and malignant), inflammatory conditions, benign giant cell tumors, angiomas (benign and malignant), Ewing's tumor and myeloma. Each division, so far as is possible, the author defines and