Osseointegration was discovered in 1962 and coined as a term in 1977. Original definitions implied direct contact between foreign materials and bone without any interposed soft tissue layers. Today, osseointegration is regarded to be a foreign body response to separate foreign elements from bone. A new definition of the term is suggested in this paper; “Osseointegration is a foreign body reaction where interfacial bone is formed as a defense reaction to shield off the implant from the tissues”. Excellent clinical results of osseointegrated implants have been reported from dentistry and Ear Nose Throat surgery, the latter with the indications of a stable anchorage of hearing aids or facial epistheses in cases of facial trauma. In Orthopaedic surgery a randomized controlled clinical trial has been undertaken demonstrating very good clinical results supported by positive radiostereo-photogrammetical data.