beta-Adrenergic-inhibiting drugs are widely prescribed for the treatment of hypertension. These drugs have previously been found to influence a variety of psychologic and behavioral functions and have, in some cases, been associated with serious psychiatric side effects. The present study examined psychologic changes associated with beta-blockade therapy. Twenty-six men with mild hypertension (diastolic blood pressure 90 to 110 mm Hg) were randomly assigned to receive either a selective beta 1-antagonist (atenolol), a nonselective beta 1- and beta 2-antagonist (propranolol), or a placebo. Both before and after a 2-week period of drug administration, subjects completed a comprehensive assessment of quality of life including measures of mood, memory performance, and side effects. In general, beta-blocker therapy was associated with relatively few adverse symptoms, particularly when compared with control subjects taking placebo. Reductions in negative emotional states (tension and anger) were observed for subjects receiving atenolol, and the largest improvements in memory performance were observed for subjects receiving propranolol. These results suggest that beta-blocker therapy is not invariably associated with negative side effects and that some behavioral functions may actually be improved.