The hydrochloride salt of alfuzosin, a quinazoline compound with smooth muscle-relaxing activity. Alfuzosin selectively binds to and antagonizes post-synaptic alpha1-adrenoreceptors in smooth muscle of the prostate, bladder base, bladder neck, prostatic capsule, and prostatic urethra, initiating relaxation of smooth muscle and resulting in improvement of urine flow and the symptoms of benign prostatic hyperplasia (BPH). This agent also blocks alpha1-adrenoreceptors in peripheral vascular smooth muscle, resulting in vasodilatation and a decrease in peripheral vascular resistance.