BACKGROUND The aim of this study was to retest the hypotheses of Reekie and Devlin (1998) by conducting a similar randomized controlled trial in an orthodontic clinic in the Netherlands. It was hypothesized that a reminder would reduce the failed attendance rate and that the form of the reminder would be irrelevant. METHODS All patients with appointments in the orthodontic clinic at the Academic Centre of Dentistry Amsterdam during a 3-week period were divided into 4 groups. Three groups received a reminder 1 day before the appointment, either by telephone, mail, or short message service (SMS, a service used to send and receive short text messages to and from cell phones). A control group did not receive a reminder. In a follow-up study, random subsamples in each group were interviewed by telephone. Subjects were asked how they felt about receiving a reminder and which reminder they preferred. RESULTS The hypothesis that a reminder would reduce the failed attendance rate was not confirmed. Also, no differences were found between the 4 conditions, indicating that the form of the reminder is irrelevant. However, most of the interviewed participants felt positive or very positive about receiving a reminder. There was a significant preference for a reminder by mail (56.3%), followed by a telephone reminder (26.0%) and a reminder by SMS (17.7%). No less than 20% of the interviewed participants felt negative or very negative about the reminders and considered them to be a waste of time and money. CONCLUSIONS The hypothesis that reminders are useful in the prevention of failed appointments was not confirmed. This study underlines the importance of replication studies. It demonstrates that every research result, whether it is generated by evidence-based or tradition-based research, should be interpreted with care and should be replicated in other studies before the results can be generalized.