The objective of this study was to compare the efficacy and safety of bipolar transurethral resection in saline (TURIS) and conventional monopolar transurethral resection (TURP) in men with voiding difficulties due to high volume (>60g) benign prostatic hyperplasia. Between May 2005 and January 2009, 66 men with bladder outlet obstruction due to large benign hyperplasia (BPH) (>60 g) underwent transurethral resection, either by Olympus monopolar or Olympus bipolar TURIS technique. Perioperative and outcome data were recorded and compared. There was no significant difference in patient age, prostate size, PSA, uroflow rate, post voiding residual urine, operation time, catheterization time, and hospital stay. In the monopolar TURP group, an important drop in serum sodium was observed (3.12 mmol/L), statistically significantly different (p = 0.012) from the 1.30 mmol/L drop in the bipolar TURIS group. One case of clinical TUR syndrome was observed in the conventional monopolar TURP group. Early and late complications such as clot retention, urinary retention, bladder neck stenosis, and urethral stricture were identical in both groups. The bipolar TURIS device is a valid treatment option for patients with BPH-related voiding disorders due to high volume BPH. Obviating the risk of TUR syndrome, this minimally invasive procedure may be a good surgical option in the urologist's armamentarium.