The dynamic obstruction of the bladder outlet secondary to benign prostatic hyperplasia (BPH), and the contractile properties of the human prostate are mediated primarily by α 1-adrenoceptors. There are now at least three subtypes (A, B, and D) of α 1-adrenoceptors, and recent work revealed that α 1A-adrenoceptor and α 1B-adrenoceptor may have a prime role for prostatic obstruction, and contraction of artery, respectively. Very recently, the presence of a low affinity α 1-adrenoceptor for prazosin, named α 1L, in the human BPH tissue has been determined. Because the DNA sequence of α 1L-adrenoceptor has not yet been cloned, the α 1L-adrenoceptor may be another form of the α 1A-adrenoceptor, or another pharmacologically distinct α 1-adrenoceptor which mediates the norepinephrine-induced contraction of the prostatic smooth muscle. Furthermore, the contribution of α 1-adrenoceptors in the prostate to symptoms (not only obstructive, but irritative symptoms) which are elicited by prostatic obstruction remains to be determined.