Although earlier studies on the incidence and etiology of childhood hypertension would lead one to believe that hypertension in this age group is most commonly secondary in nature, experience in our clinic and others strongly suggests that states of elevated blood pressure observed in preadolescent or adolescent subjects more closely resemble the adult form of 'essential' hypertension in many cases. As larger numbers of hypertensive children requiring chronic medical management are identified, the acute and long-term effects of antihypertensive agents will become of increasing importance to physicians and other health professionals. At the present time longitudinal studies of sufficient duration have not been conducted to allow accurate assessment of the effect of antihypertensive drug therapy on morbidity or mortality when treatment is initiated during childhood or adolescence. The decision to initiate antihypertensive therapy carries significant implications of a social and economic as well as a medical nature. It is incumbent upon the physician to carefully document the presence of sustained hypertension during a series of office examinations and to subject each patient to a thorough evaluation searching for secondary causes of hypertension prior to initiating treatment. A uniformly successful regimen for the treatment of hypertension does not exist. Experience dictates, however, that the application of certain therapeutic principles discussed in the present text can maximize antihypertensive effectiveness and minimize noncompliance. The judicious use of serum drug levels when available can be of inestimable assistance in this regard.