PURPOSE: To improve TIPS patency by inserting polytetrafluoroethylene(PTFE)-covered spiralZ-stents in swine. MATERIALS AND METHODS: Using PTFE covered spiral Z-stents lined with TIPS tract from theportal vein wall to the inferior vena caval orifice of the right hepatic ve i n , TIPS were created in seven youngswine. The animals were followed up by portal ve n o g r a p hy and venous pressure was measured at two - weekintervals for 12 weeks or until shunt occlusion. After sacrifice, resected liver was examined grossly andpre-pared for histology. RESULTS: The fifty percent patency rate using lifetime analysis was 83 % at 4 weeks, 33%at 6 weeks, 17 % at 8 weeks and 0% at 10 weeks. Venography demonstrated that the predominant sites of stenosiswere the portal vein wall(2/6), the TIPS tract(2/6) and the IVC orifice of the right hepatic vein(2/6). One swinedied 11 days after TIPS due to illness, and bile leaks were discovered in two of the seven animals. Histologicstudy demonstrated intimal hyperplasia in either the portal vein wall or the end of the stent at which the IVCorifice was located, as well as thrombus and pseudointimal hyper-plasia in the TIPS tract. CONCLUSION: P T F E -c overed spiral Z-stents were easily placed and significantly im-proved TIPS patency.