This study examined the effects of atenolol and metoprolol on neuropsychologic functioning, mood, sedation, and sleep. Following tapering of antihypertensive medication and a 3-wk placebo washout, 35 hypertensive patients were randomized to receive double-blind either atenolol or metoprolol for 4 wk. There was no consistent evidence that beta blocker treatment was associated with a deleterious effect on neuropsychologic functioning. The neuropsychologic effects of the drugs did not differ. There were also no significant changes in mood as assessed by the Profile of Mood States as a consequence of treatment with a beta blocker. However, there was a trend for patients receiving metoprolol to report a poorer mood profile. There was no overall or differential drug effect on deep sleep or sedation. On both drugs, however, patients complained of disturbing dreams (p less than 0.04); however, the two drugs did not differ in this regard. On both medications patients had substantial complaints of fatigue; however, it is inappropriate to attribute this to the medication since there were equivalent complaints on placebo.