Broken appointments are a major problem in many health facilities. Many studies have shown that broken appointments can be significantly reduced by mailing out appointment reminder cards. One of the first such studies was done at the Anthony L. Jordan Health Center in 1972 and showed that use of such reminders resulted in kept-appointment rates of 64% compared with 48% for control studies. Subsequently, routine use of such reminders was instituted. In March 1980, a follow-up study was conducted at the same health center to determine whether mailed reminders were still effective in reducing broken appointments. A 20% systematic random sample of 766 scheduled March appointments had their reminder cards held; the remaining 80% were mailed reminders as usual. Results showed no significant differences in "keep rates" between the two groups: 64% in those with reminders compared with 62% for those without. These findings suggest that effectiveness of mailed appointment reminders on reducing broken appointments may decrease with time.