Poor drug adherence to prescribed drug treatments and lifestyle recommendations is a major determinant of poor blood pressure control reported around the World. Prevalence rates of antihypertensive medication nonadherence are highly variable depending on the studied population and may reach up to 40%. Remarkably, the phenomenon stays often undiagnosed and unaddressed mainly because physicians have limited tools to perform a reliable diagnosis. In this review oriented toward practicality, 5 principal aspects of nonadherence will be addressed with a special emphasis on psychological factors influencing adherence patterns, both from a patient's and physician's perspectives.