Twenty-one patients with benign prostatic hypertrophy (BPH), and a weight of transurethrally resected tissue exceeding 80 g (Group 1), were compared to a control group of 30 patients with a weight of resected tissue less than 80 g (Group 2) with regard to the peri- and postoperative course and the symptomatic and urodynamic results of surgery. All patients were followed 12 months postoperatively. In both groups more than 90% of the patients were satisfied with the results of the operation. However, the obstructive symptoms were better relieved than the irritative symptoms. The group who had large resections performed had a longer operating time and a greater perioperative blood loss than the group of minor resections. No differences were found with regard to other peri- or postoperative complications or subjective results. Transurethral resection is safe and efficient in treating BPH, also with very large prostates.