As compared to other techniques MRI offers many advantages. It enables one to differentiate the nucleus pulposus within the disc and reveals the discal degeneration. It reveals more precisely the relationships with nervous formations and it is invaluable for the detection and exploration of bone tumors and metastasis, of deformations, of the cervico-occipital junction, of the cervical and dorsal medullar lesions and of infectious processes. As for peripheral joints, it seems to be useful in the study of deposits, infections of bones or joints, osteonecrosis, algodystrophy. It also proves useful in the exploration of the synovialis of inflammatory rheumatism, of metabolic arthropathy, of lesions in the tendons, muscles, menisci or ligaments. It is not quite as interesting for arthritis and chondrocalcinosis but further developments may alter this situation.