The prostatic UroLume Wallstent was positioned in 30 poor operative risk patients with bladder outlet obstruction due to benign prostatic hyperplasia. Preoperatively, 12 patients (40%) could still void spontaneously (group 1), while 18 (60%) had an indwelling catheter (group 2). Preoperative and postoperative assessment included scoring of subjective symptoms, physical examination, uroflowmetry with maximum flow nomogram, transrectal ultrasonography of the prostate, determination of residual urine volume and cystourethroscopy. All but 1 patient could void spontaneously after insertion of the stent. In group 1 preoperative and 1-year followup mean (plus or minus standard error) peak flow rates were 8.0 +/- 0.7 ml. per second and 15.8 +/- 1.8 ml. per second, respectively (p < 0.01), the mean residual urine volumes were 127 +/- 27 ml. and 38 +/- 11 ml. (p < 0.05), respectively, and the mean maximum flow nomograms (plus or minus standard deviation) were -2.6 +/- 0.1 and -1.4 +/- 0.4, respectively. In group 2 the 1-year followup mean peak flow rate, residual urine volume and maximum flow nomogram were 13.2 +/- 0.8 ml. per second (standard error), 32 +/- 14 ml. (standard error) and -1.5 +/- 0.1 (standard deviation), respectively. According to the maximum flow nomogram values all patients were nonobstructed postoperatively. At 1 year the stent was completely covered by prostatic epithelium in 90% of the patients, while in the remainder it was still partially visible at urethroscopy. Transrectal ultrasonography had an essential role in patient followup by accurately assessing the position of the stent. Placement of this prostatic stent is safe and effective for selected benign prostatic hyperplasia patients who cannot undergo surgical treatment due to poor operative risk.