The twelve years that have elapsed since the second edition of this book have witnessed the introduction of a number of new entities in neoplasms of bone and in skeletal diseases of unknown etiology. The increase in the scope of the book has led to the inclusion of new chapters, such as those devoted to fibrous dysplasia, osteoid osteoma, tumors of the spine, endocrine changes in bone and rare diseases of bone. The chapters on embryology of bone and chondroblastomas as well as the chapter on treatment of sarcoma of bone have been rewritten. The classification of bone tumors, which represent the fundamental material on which this book is based, has been extended to include more than 500 additional cases. More than 100 new illustrations have been added and a large number of old ones replaced. The authors have presented the best reproductions of representative roentgenograms, gross specimens and photomicrographs.