This study compared the effects of general and regional anesthesia on cognitive and psychosocial functioning in elderly persons. Sixty-four patients between 60 and 86 yr of age undergoing knee arthroplasty were randomly assigned to receive either general or regional anesthesia. A battery of psychometric tests, including the Satz-Mogel form of the Wechsler Adult Intelligence Scale-Revised, the Wechsler Memory Scale-Revised and the Sickness Impact Profile, and various neuropsychological measures were administered by a blinded observer just before surgery and again 3 months later. Analyses of covariance revealed improvements in most measures that were equivalent between groups. The results indicated that there were no cognitive or psychosocial effects of general or regional anesthesia after 3 months in elderly persons undergoing knee arthroplasty. In this patient population, general anesthesia poses no more risk to long-term mental function than regional anesthesia.