Ambulatory blood pressure monitoring (ABPM) is being used increasingly for the evaluation of antihypertensive agents in clinical trials. In this brief review several aspects of ABPM are discussed. In particular, attention is paid to the extent to which ABPM is subject to a placebo response and the extent to which the sample size of the study population can be reduced with this type of measurement. In addition, some remarks are made with regard to how selection of patients with this methodology can be improved and how it may be used as a tool to evaluate the duration of action of antihypertensive agents. Finally, some potential disadvantages of ABPM as compared to conventional clinic blood pressure measurements are discussed
