With widespread use of balloon dilatation catheters outside the vascular system, percutaneous balloon dilatation has become an accepted alternative to surgery. Seventeen patients who developed ureteric stenosis following renal transplantation underwent 21 transrenal angioplastic balloon dilatations. Fifteen patients had lower ureteric strictures (2-22 mm long), and two had multiple strictures. The time interval between transplantation and obstruction ranged from 11 to 1370 days (median 71, mean 228.9 days). Nine patients were treated successfully (53%) with no stricture recurrence during the follow-up period, which ranged from 3 to 44 months (median 16, mean 17.8 months). In eight of nine patients in this group, the stricture impression on the inflation balloon was eliminated, and this appears to correlate best with a successful outcome. The eight patients who failed balloon dilatation and restenosed, did so within 7-42 days in seven patients; one patient had late stricturing at 238 days. Serious complications occurred in only one patient, who developed an A-V fistula not amenable to correction and necessitating transplant nephrectomy.