although the male reproductive system diseases are not restricted to the prostate, this is one of the most interesting organs for the urologic medical practice. the benign prostatic hyperplasia (bph) represents a tissual increase of these histological elements causing profound alterations in the prostate organisation. therefore this study aims at evaluating the glandular lumen volumetric density (vv) the transition zone (median lobe) in human normal prostates compared with hyperplastic ones (bph). controls consisted of 10 samples of prostates transition region obtained during necropsy of young adults victims of accidents. samples of prostatic tissue of the transition zone were obtained from 10 patients with clinical symptoms of bladder outlet obstruction and histopathological diagnoses of the bph submitted to transvesicalprostatectomy. samples of the 5mm were stained on paraffin sections of prostate using hematoxilin-eosin. for the quantitative analysis the stereology method assisted by a software program was used to verify the vv. the glandular lumen volumetric density showed the significant statistically bph increase, which seems to be related to the bladder outlet obstruction and to the stasis of the luminal contents, causing intraluminal pressure in turn deformations in the glandular with probable consequences in the epithelium, well the to the secretory alterations.