The clinical, radiological and histological information on the fate of Kiel bone implants for anterior spinal fusion in four patients was evaluated. These implants were found to be unsatisfactory and further operations were required. Biopsies of the grafts showed that the Kiel bone was invaded by fibrous tissue but that it did not ossify or become incorporated into the underlying bone. However, it might provide temporary support to the grafted area. These findings indicate that the use of Kiel grafts does not seem to be justified in current orthopaedic practice.