This invention is directed to morpholinone and morpholine derivatives which are selective antagonists for human &agr;1a receptors. This invention is also related to uses of these compounds for lowering intraocular pressure, inhibiting cholesterol synthesis, relaxing lower urinary tract tissue, the treatment of benign prostatic hyperplasia, impotency, cardiac arrhythmia, sympathetic mediated pain, migraine, and for the treatment of any disease where the antagonism of the &agr;1a receptor may be useful. The invention further provides a pharmaceutical composition comprising a therapeutically effective amount of the above-defined compounds and a pharmaceutically acceptable carrier.