The aim of this study was to evaluate the feasibility of coaxial approach in difficult-to-cross lesions in patients with failed percutaneous transluminal renal angioplasty by conventional over-the-wire exchange technique. Twelve stenoses in 10 patients (six women and four men; age range 19 +/- 7 years) with uncontrolled hypertension were treated by this method. The stenosis was caused by nonspecific aortoarteritis in 8 patients and fibromuscular dysplasia in 2 patients. It was ostial in seven and post-ostial in five vessels. Conventional exchange technique was unsuccessful in all of them. All procedures were done by femoral route. Technical success was seen in 11 (92%), without complication. The stenosis improved from 90 +/- 2.1% (range 80-100%) to 6 +/- 7% (range 0-20%), blood pressure decreased from 198 +/- 12.3 mm Hg (range 180-220 mm Hg)/130 +/- 6.7 mm Hg (range 120-140 mm Hg) to 119 +/- 5.7 mm Hg (range 110-130 mm Hg)/83 +/- 3.9 mm Hg (range 80-90 mm Hg), and number of drug treatments for hypertension fell from 3.6 +/- 0.52 (range 3-4) to 1 +/- 0.94 (range 0-3; p < 0.01). Percutaneous transluminal renal angioplasty resulted in "cure" in 3 patients and "improvement" in 7 patients. Follow-up period was 3-21 months (mean 6.4 months). No restenosis was detected. Coaxial approach is safe and effective in treating difficult-to-cross lesions in which renal angioplasty by conventional exchange technique is unsuccessful.