While cardiovascular disease remains the most common cause of death in older adults, treatments are now available that are associated with significant improvements in both morbidity and mortality. The Cardiovascular Health Study trials of drug use in older adults reviewed here show that in a racially and geographically diverse cohort of community-dwelling elders, effective treatments were underused during the 1990s. Most participants with hyperlipidemia, atrial fibrillation, and congestive heart failure did not receive therapies known to reduce morbidity and mortality, and when treatment was initiated, those at highest risk were no more likely to start treatment than those at lower risk. The use of drugs with evidence of efficacy in the prevention of stroke and congestive heart failure in hypertensive participants decreased with time, and control of hypertension and hyperlipidemia were particularly low in diabetics. The impact of this undertreatment on older persons and on society is likely to be substantial.