In recent years, there has been a spate of articles on the failure of patients to take medicine as directed and the impact of this on therapeutic outcome. Many of these studies have been reviewed by Stewart and Cluff1 and by Blackwell.2 They disclose a disturbing rate of noncompliance ranging from 20% to 82%. In one study, individuals judged to be very unreliable were excluded.3 Even with this restriction, 31% of the "reliable" patients took less than 70% of their medication. The magnitude of the patient noncompliance problem is even greater than the data indicate, because most of the methods for measuring compliance are limited to finding the extremes only—those who comply fully, or those who comply minimally or not at all. The majority of patients in compliance studies were taking divided doses of a single drug. A substantial number of patients today, however, are simultaneously taking