Renal artery stent placement with use of the Wallstent endoprosthesis. The Wallstent endoprosthesis was placed in 12 renal arteries of 11 patients; a total of 15 stents were placed. Indications for placement were restenosis after dilation and insufficient result after dilation. In two patients, malpositioning of the stent required placement of a second stent. Complications included a case of massive cholesterol embolization and a case of unexplained transient hematuria, proteinuria, and deterioration of renal function. At repeat angiography of seven renal arteries after stent placement, one was occluded and required thrombolysis and dilation. Another showed restenosis due to shortening of the stent and required redilation and, later, placement of another stent. This stent became occluded after 1 month. In this patient and in three other cases, angiography disclosed tissue buildup in the stent but without significant stenosis after this short-term follow-up. After a clinical follow-up of 6.7 months +/- 3.4 in 10 patients treated for hypertension, three were cured, four were improved, and three were unchanged when blood pressure levels before stent placement were compared with those obtained after stent placement. 