The decision to use diastolic blood pressure as the basis for therapeutic intervention for hypertension was based primarily on clinical trials experience. The majority of observational studies shows as great or greater risk for elevated systolic blood pressure readings. Even many of the clinical trials in which a posteriori analyses have been performed confirm a greater effect of systolic rather than diastolic blood pressure as a predictor of coronary heart disease mortality. The current practice of using diastolic blood pressure readings as the sole treatment criterion should be reexamined in light of the observational studies and clinical trials reviewed here.