Fifteen patients, aged 8 to 17 years, were found to have hpertension and were studied from February 1974 to Decemober 1975. Hypertension was defined as supine diastolic blood pressure repeatedly above 90 mm Hg. Five patients had a family history of hypertension. Extensive diagnostic evaluation performed in all cases failed to show an underlying cause for the hypertension. Patients with target-organ involvement were treated with hydrochlorothiazide; five of them are currently normotensive. Of the remaining nine untreated patients, four became spontaneously normotensive within eight to 14 months of the initial evaluation. These results suggest that extensive studies in children with hypertension may not be necessary in every case if clinical findings meet the critiera for the diagnosis of essential hypertension. These studies might be desirable, however, if target-organ involvement is present.