Introduction: This study was undertaken to investigate the effects of two different alpha 1-adrenergic blockers on bladder hypertrophy using ultrasound-estimated bladder weight (UEBW) and to assess the relation between changes in UEBW and other objective and subjective parameters of disease severity in patients with benign prostatic hyperplasia (BPH). Materials and Methods: 41 men were enrolled in the study and they were subjected to either watchful waiting (group 1) or alpha 1-adrenergic receptor blocker therapy ( group 2 with alfuzosin; group 3 with tamsulosin). The patients were investigated by symptom evaluation using the International Prostate Symptom Score ( IPSS) and quality of life score ( QOL), uroflowmetry and UEBW. The parameters were assessed again 3 months after initiation of treatment and compared with the initial values. Results: While the mean UEBW increased in group 1(42.2 +/- 10.3 to 52.5 +/- 12.2 g), it decreased in both the other groups that received alpha-blocker therapy (61.3 +/- 18.7 to 41.1 +/- 13.2 and 59.4 +/- 17.2 to 43.5 +/- 17.6 g, respectively). In groups 2 and 3, the mean UEBW, post- void residual urine, IPSS and QOL values decreased, and the mean maximum flow rate increased. All of the changes in group 2 and all except QOL in group 3 were statistically significant (p < 0.05). The changes correlated well with each other with regard to treatment success. The highest decreases in UEBW were encountered in patients with heavier bladders. Conclusions: UEBW decreases with alpha(1)-adrenergic receptor blockers. When used together with the other objective and subjective parameters, UEBW is a promising quantitative parameter as a follow-up tool and can be useful in monitoring the therapeutic effects of alpha 1-adrenergic receptor blockers. Copyright (c) 2006 S. Karger AG, Basel.