Classification schemes for hypertension are necessary. They provide us with definitions for when hypertension begins and help us to assess risk, determine prognosis, and guide management. Systems in current use rely on either the level of blood pressure (diastolic, systolic, or both) and classify patients based on the level of relative risk (the proportional likelihood of cardiovascular events occurring as blood pressure rises), absolute risk (the actual odds that a patient or a population will develop an event), or both. Absolute risk reflects the sum of all the factors that contribute to the likelihood that a patient will experience cardiovascular disease. The system we propose stages hypertensive individuals on the basis of blood pressure level (as does the Fifth Joint National Committee report on the detection, evaluation, and treatment of high blood pressure [JNC-V] and the World Health Organization/International Society of Hypertension guidelines) but uses different levels for each stage than do the previous systems and then modifies the numerical stage with the subscript "c" for complicated (when target-organ damage and/or other cardiovascular risk factors are present) or "u" for uncomplicated (when they are absent). The data obtained from a complete medical history and physical examination and a few inexpensive laboratory tests provide the information a provider needs to classify an individual as being complicated or uncomplicated. This system also provides a guide to treatment, as drug therapy would be used sooner in individuals with complicated hypertension, and we propose that compensation for providers be higher when they are caring for a patient with complicated rather than uncomplicated hypertension. (Hypertension. 1996;28:719-724.)