Benign Prostatic Hyperplasia (BPH) usually occurs in males 45-50 old and progressively involves 75% of the male population over 75 years of age. The clinical manifestations of BPH are related primarily to bladder outlet obstructions resulting from enlargement (mechanical component) of the prostate gland, and from extrinsic and intrinsic sympathetic activation of alpha-adrenoceptors (dynamic component) present in the prostatic muscle tissue, prostatic urethra, bladder base and neck. Several drugs have been employed in the last decades: LHRH analogs (Leuprorelin and Goserelin) which can reduce the testicular production of androgens with reduction in prostate size; Serenoa repens for its anti-androgenic and anti-estrogenic activities; Finasteride (5-alpha-reductase inhibitor) which blocks the conversion of testosterone into the more active dihydrotestosterone. Finally, the alpha 1 blocking agents (Terazosin, Doxazosin, Tamsulosin) that improve urinary symptoms by acting on dynamic component. Clinical improvements derive from their antagonist action on alpha 1 adrenergic receptors which mediate contraction of the prostate gland, proximal urethra, bladder base and neck, with the consequent reduction of urethral pressure, bladder outlet resistance, and increase of urinary flow. Due to its pharmacodynamic and pharmacokinetic properties, as well as the clinical results obtained, Terazosin, alpha 1 blocker, appears to be particularly useful in the treatment of patients with mild- to moderate symptomatic BPH.