The symptomatic treatment of benign prostatic hyperplasia with alpha-adrenoceptor antagonists is based on the concept of a dynamic component in prostatic obstruction, dependent on the sympathetically controlled tone of smooth muscle in the prostate and its capsule. Blockade of the alpha adrenoceptors minimizes this tone, hence the degree of obstruction, and also relieves the irritative symptoms. A review of the published clinical experience reveals convincing evidence of a beneficial action on the irritative symptoms of diurnal and nocturnal frequency, and on the objective parameters of uroflow, residual urine, urethral closure pressure, and cystometrographic evidence of detrusor instability. It is also of value in the prophylaxis or treatment of certain cases of acute retention in these patients. The greatest amount of experience has been with phenoxybenzamine, which appears to be the most effective drug in practice, but other drugs are being assessed for this purpose. It is possible that a combined alpha 1 and alpha 2 antagonist may be more effective than a pure alpha 1 antagonist.