OBJECTIVE To review published evidence on the use of ambulatory and self-measurement devices in the diagnosis and management of hypertension. METHODS Computerized literature searches and manual review of bibliographies. METHODS Articles documenting original research pertaining to the diagnosis, treatment, or prognosis of hypertension using ambulatory or self-measurement devices. RESULTS Studies that have compared office, self-measured, and ambulatory blood pressures have documented substantial, but nonsystematic, differences. Such findings have raised concern over the appropriateness of diagnosing hypertension and initiating drug therapy in individuals with high office blood pressure but comparatively low self-measured or ambulatory blood pressure ("office" or "white coat" hypertension). Evidence from a large number of cross-sectional studies and a single prospective study suggests that blood pressure- related end-organ damage is more closely associated with ambulatory than with office blood pressure. Less evidence supports self-measured blood pressure in this regard, and data are insufficient to compare ambulatory and self-measured blood pressure in terms of cardiovascular disease risk prediction. The estimated resource cost of an ambulatory blood pressure test is approximately $120, whereas charges range from $100 to $450. The annualized resource cost of blood pressure self-measurement is $50 or less. On a national level, the annual direct costs of ambulatory blood pressure monitoring could be as high as $6 billion, if this technique were used routinely to diagnose and monitor hypertensive patients. The extent to which direct costs would be offset by savings from less frequent or more efficient treatment for hypertension cannot be estimated reliably. Several practical and technical issues also detract from the potential usefulness of ambulatory and self-measurement devices. Finally, there is some evidence that office blood pressures measured by well-trained nonphysicians may serve as an alternative to ambulatory and self-measurement techniques in estimating usual blood pressure. CONCLUSIONS Limited clinical applications of ambulatory blood pressure monitoring and blood pressure self-measurement in the diagnosis and management of hypertension appear to be warranted. Endorsement of these technologies for routine clinical use, however, will require more convincing evidence of their clinical effectiveness.