Home blood pressure monitoring (HBPM) improves blood pressure control, but little is known about its effects on medication adherence. The authors conducted a systematic review of the published literature on the effects of HBPM on medication adherence. Of 440 abstracts and citations reviewed, 11 randomized control trials met predefined criteria. Six of the 11 randomized controlled trials reported statistically significant improvement in medication adherence; 84% of these were complex interventions involving the use of HBPM in combination with other adherence-enhancing strategies such as patient counseling by nurses, pharmacists, or a telephone-linked system; patient education; and the use of timed medication reminders. Interventions conducted in primary care settings were not effective compared with those that occurred in hospital-based clinics or nonclinical settings. The data on the effects of HBPM on patients' medication-taking behavior are mixed. Future studies should investigate the independent effects of HBPM in primary care practices where the majority of hypertensive patients receive their care.