More than 1300 patients have been examined with MR for diseases of the CNS since October 1983. Eight hundred patients were studied with a resistive 0.15 Tesla system and the remaining with a superconductive 0.5 Tesla system. Lesions of the cervical spinal cord, syringomyelia and intra or extra-axial tumors, were perfectly demonstrated. The absence of artefacts in the posterior fossa, as well as sagittal and coronal slices, allow an excellent demonstration of lesions, particularly of brain stem tumors. In a large group of patients with multiple sclerosis, MR has proven to be diagnostically superior to CT, evoked potentials and CSF examination. Sensitivity is very high but specificity may be low in infra- and supratentorial gliomas. Differentiation of tumor from oedema may be difficult.