Low back pain is one of the most common diseases, however the etiology of low back remains one of the most complex problems. Conventional imaging modalities such as plane radiography, CT and MRI are effective and in many cases sufficient diagnostic modalities. These modalities are however only morphologic. Discography with " memory pain test " is the only method that permits physiopathological and morphologic exploration of low back pain. Therefore discogrophy has a useful but limited place in the exploration of low back pain.