In a placebo-controlled, double-blind crossover trial, clonidine caused a marked and significant reduction of objective signs and subjective symptoms of opiate withdrawal in thirty hospitalized opiate addicts. In an open trial of clonidine in opiate withdrawal, clonidine was found to suppress opiate withdrawal signs and symptoms, allowing all of the patients to detoxify successfully from chronic opiate addiction. Clonidine was demonstrated to reverse and suppress the signs, symptoms, and effects associated with opiate withdrawal. These data support a release from chronic opiate-induced noradrenergic inhibition producing noradrenergic hyperactivity as the pathophysiological substrate for opiate withdrawal. Clonidine replaces opiate-mediated inhibition with alpha-2 mediated inhibition of noradrenergic nuclei.