Abstract： Objective To explore the value of susceptibility weighted imaging (SWI) in detecting the changes of cerebral internal veins and their tributaries.especially the deep medullary veins,in the patients with multiple sclerosis(MS).Methods Conventional MRI and SWI were performed in 43 MS patients and 43 healthy volunteers(control group).Two groups were matched on gender and age.In the MS patients.the course of disease was less than 0.5 year in 5 paticnts,between 0.5 year and 2.0 years in 17 patients and more than 2.0 years in 21 patients.SWI venograms were obtained by performing minimum intensity projection(MinIP)reconstruction.Comparing with the control group,the changes of the cerebral internal veins,their main tributaries and the deep medullar veins in the MS patients were evaluated by 2 experienced radiologists with double blind methods.Kruskal Wallis H analysis and Wilcoxon rank test were used for statistics.Results In the 43 patients,23 had active MS(active group),20 had chronic MS (chronic group).(1)The mean score of the cerebral internal veins and their main tributaries was(1.96±0.71)for 23 active MS patients,(1.25±0.44)for 20 chronic MS patients and(3.00±0.00)for the control group,respectively.There were significant differences among the three groups(H=67.65,P<0.01).And the mean scores in the active and chronic MS patients were lower than that in the control group (1.96±0.71 vs 3.00±0.00,Z=-6.67.P<0.01:1.25±0.44 vs 3.00±0.00,Z=-7.76,P<0.01),the mean score in the active MS patients was higher than that in the chronic MS patients(Z=-3.35,P<0.01).(2)The deep medullar veins were shortened or diminished in 38 MS patients whose course of disease were more than 0. 5 year, and increased and prolonged in 5 MS patients whose course of disease were less than 0.5 year. (3) The " penetrating veins " were dilated and prolonged in 35 periventricular enhanced lesions in the 23 active MS patients, and thin and short in 80 periventricular non-enhanced lesions in the 20 chronic MS patients. However, in 3 chronic MS patients, slightly expanded and prolonged "penetrating veins" were detected in 6 periventricular non-enhanced lesions. Conclusion SWI can reveal the changes of the cerebral internal veins and their tributaries, especially the deep medullary veins, in different stages of MS patients, providing important information for pathogenesis and pathological study for MS patients.