Prehypertension--blood pressure between 120-139/80-89 mmHg--is a major public health concern. The condition is very prevalent (especially in obese young people), is often associated with other cardiovascular risk factors and independently increases the risk of hypertension and subsequent cardiovascular events. In the general population, prehypertension can be lowered, but not often reliably, by lifestyle modifications. Drug therapy for prehypertension is not yet recommended, except for individuals with diabetes, chronic kidney disease, and perhaps known coronary artery disease, because of short-term cost considerations and unproven long-term benefits. Ongoing research will probably identify which individuals with blood pressures in the prehypertensive range, but with no serious comorbidities, would benefit from treatment. In this Review, we attempt to summarize the recently published data concerning the epidemiology, attendant risks and potential treatment options for this important and growing public-health problem.