Further identification of the alpha-1 adrenoceptor present in various tissues using pharmacological and molecular biological studies has revealed that there are three subtypes of the alpha-1 adrenoceptor. This raised the possibility that there could be one subset of alpha-1 adrenoceptors within the human prostate and these might differ from those in the vascular. Binding experiments defined the functionally important alpha-1 subtype in the human prostate. It has been postulated that a drug with relatively high affinity for the alpha-1 adrenoceptor may be "prostate-selective". Such a drug may be as effective as other alpha-1 adrenoceptor antagonists but may have less effect on blood pressure and cause fewer vasodilatory side effects. The safety profile of non-subtype selective and subtype selective long-acting alpha-1 blockers is considered. However, Quantitative analysis showed that the amount of alpha-1a receptor differs from biopsy to biopsy, suggesting that prostates will differ in their response to an alpha blocker even when it is alpha-1a selective. Polymerase chain reaction (PCR) technique can be used to determine quantitatively alpha-1a receptor in small amount of tissue; at present, however, no non invasive parameters have been tested.