AIM:To study the stability of portal hypertension (PHT) caused by partial ligation of the portal vein ligation (PVL) in a rat model.METHODS:Thirty male adult Wistar rats were divided into two groups:10 in Group Ⅰ received a sham operation;and 20 in Group Ⅱ received partial PVL.Portal vein pressure (PVP) was measured at four time periods:before ligation,2 wk,6 wk and 10 wk postsurgery.Portal venography,blood sampling and liver and spleen pathological examinations were conducted at 10 wk after surgery.RESULTS:The PVP was 9.15±0.58 cmH2O before ligation,and increased to 17.32±0.63 cmH2O 2 wk after PVL.By repeat measurement of the PVP in each rat,it was shown to remain elevated for 10 wk.There were no significant differences in the pressure measurements at 2 wk,6 wk and 10 wk.Varices were found mainly in the mesenteric vein 2 wk after PVL,which were more obvious later,while these manifestations were similar at week 6 and week 10.Portal venography demonstrated the varices and collaterals.There was no significant change in liver pathology.The volume of the spleen was enlarged 2-fold after ligation,and the sinus of the spleen was enlarged due to congestion.Significant sinus endothelial cell proliferation was observed,but no evidence of hypersplenia was found on hemogram and biochemical examination.CONCLUSION:These findings suggest that a satisfactory prehepatic PHT rat model can be obtained by partial ligation of the portal vein,and this PHT rat model was stable for at least 10 wk.