In this study measurements were obtained from 359 vertebrae and 215 intervertebral discs in an attempt to classify discs by their size. At the cervical and thoracic levels, this attempt was unproductive because of extensive variations. In the lumbar spine, discs were allocated to six size-matched groups and to two height-matched groups. The breadth of marginal rims were also measured with a view to provide surgeons operating on the spine with precise data on disc morphology to facilitate disc replacement.