Congenital and acquired bone defects constitute a central problem of traumatology and orthopedics. In order to cure these defects it is often necessary to fill up the bones operatively with suitable substances. Recently, so-called bone substitutes (collagen, gelatine, bone matrix, calcium phospate, hydroxyapatite) have also been recommended. Following an introductory presentation of bone regeneration and transplants, these substitutes are discussed here in a comprehensive survey of the literature. Particular attention is given to the significance of mineral substance such as hydroxyapatite, which will undoubtedly find a place in bone surgery owing to its outstanding bioactivity and biotolerance. The implants examined are also of significance for maxillofacial surgery and dentistry. The histologic techniques in the staining of undecalcified bone preparations and in histomorphometry are presented in a special chapter.