Holmium laser enucleation of the prostate (HoLEP) is a surgical treatment for bladder outlet obstruction secondary to benign prostatic hyperplasia. HoLEP is a transurethral procedure that uses the holmium laser fiber (wavelength 2,140 nm) to dissect whole prostatic lobes off of the surgical capsule in retrograde fashion, while maintaining excellent hemostasis. The lobes are removed from the bladder by a purpose built transurethral morcellator, which means that large volume prostates can be enucleated endoscopically. We compared this procedure with transurethral prostate resection (TURP) in a randomized trial by evaluating outcomes in patients with a prostate volume of 40 to 200 ml on transrectal ultrasound. A total of 61 patients with urodynamically proved bladder outlet obstruction secondary to benign prostatic hyperplasia were randomized to TURP or HoLEP. Perioperative parameters recorded included resectoscope, laser, electrocautery, morcellation and catheter time, hospital stay, bladder irrigation, volume blood transfusion the rate and resected tissue weight. Patients were followed 1, 3, 6 and 12 months postoperatively with peak urinary flow rate measurement and quality of life and American Urological Association symptom scores. Patients also underwent urodynamic assessment at 6 months with measurement of peak detrusor pressure at maximal flow, post-void residual volume and prostate volume by transrectal ultrasound. Continence, potency and all adverse events were recorded at each visit. HoLEP was superior to TURP in terms of mean catheter time (17.7 +/- 0.7 vs 44.9 +/- 10 hours) and hospital stay (27.6 +/- 2.7 vs 49.9 +/- 5.6 hours) but it required more time to perform (62.1 +/- 5.9 vs 33.1 +/- 3.7 minutes). More prostate tissue was removed in the HoLEP group (40.4 +/- 5.7 vs 24.7 +/- 3.4 gm). HoLEP was also superior to TURP in terms of relieving urodynamic obstruction at 6 months of followup (postoperative detrusor pressure at maximum flow 20.8 +/- 2.8 vs 40.7 +/- 2.7 cm H2O). HoLEP and TURP led to significant improvements in peak flow rates, symptom scores and quality of life scores compared with baseline and there was no significant difference between the 2 procedures with respect to these parameters at 12 months. Fewer adverse events were recorded in the HoLEP group. HoLEP is superior to TURP for relieving bladder outlet obstruction in men with benign prostatic hyperplasia. It allows more rapid catheter removal and hospital discharge. It requires more time to perform than TURP but more prostate tissue is removed, resulting in similar efficiency in tissue retrieval. HoLEP is equivalent to TURP in relieving men of lower urinary tract symptoms and in improving peak urinary flow rates at 12 months of followup.