Twenty patients diagnosed as having multiple sclerosis (MS) were examined by MRI and 9 neuropsychological scales: MMSE, BCRS, RMB, SDMT, BNT, VM, FAS, Benton and Hamilton. The number and distribution of the lesions, and cerebral and corpus callosum atrophy were evaluated by MRI. MR images were generated by a 0.5 Tesla instrument utilizing T1WI, PD and T2WI imaging techniques. The results reveal (1) that patients with MS are impaired in a broad range of cognitive functions but mainly memory is affected; (2) number of lesions in the corona radiata, insula and hippocampus is correlated with cognitive impairment, and (3) enlargement of the IIIrd ventricle is an indicator of memory impairment in MS patients.