Abstract: Objective: To summarize the clinical and MRI characteristics of multiple sclerosis(MS) and to improve the diagnosis of the disease.Methods: The clinical manifestation and MRI appearance of 42 cases of MS were analyzed retrospectively.Results: MS was commonly seen in young and middle aged females and the onsets were acute or subacute.Twenty-six of the cases had evoking factors before onset,which were mainly relevant to infections.Weakness and visual deterioration were the most common initial symptoms.Thirty-two of the cases had relapses.The lesion was observed in the spinal cord in 29 cases,in the optic nerve in 28 cases,in the cerebral hemisphere in 14 cases,in the brain stem in 8 cases and in the cerebellum in 4 cases.Fourteen cases had paroxysmal symptoms.As shown by MRI,the intra-brain focus was mainly located around the lateral ventricles and corpus callosum.Oval lesion was the most common form.Most of the lesions were closely adjacent to the lateral ventricle or their long-axis was perpendicular with the tangent line of the lateral ventricle.Intra-spinal foci were in the cervical and thoracic cord,which were long-strip or multiple noncontinuous fusiform,and located posteriolaterally in the spinal cord.After treatment with corticosteroids,most of the focal lesions were reduced or disappeared.Conclusions: Diagnosis of MS could be improved by combining the clinical manifestation with the MRI of brain and spinal cord.