The course and outcome of the pregnancies of 58 patients with mild chronic hypertension were studied. Twenty-nine patients were maintained on antihypertensive therapy for the duration of their gestation and 29 received no treatment. Thirteen untreated patients (41.3%) developed pregnancy- aggravated hypertension. In contrast, only 4 treated women (13.7%) suffered aggravation of the hypertensive process during pregnancy. This difference was significant (X2=5.28, P<0.05). AlI 4 treated patients who developed aggravated hypertension delivered compromised infants, while only 5 of the 13 untreated patients with this complication had poor fetal outcome. This significant difference (P=0.05) suggests the possibility that hemodynamic alterations caused by antihypertensive therapy may generate a labile fetal homeostasis which will quickly deteriorate under the added insult of aggravated maternal vasoconstriction. Furthermore, our results suggest that antihypertensive treatment is indicated for maternal but not for fetal reasons in patients with mild chronic hypertension and pregnancy. A variety of indexes of fetal well-being were evaluated with the finding of an elevated number of false-positive and false-negative correlations. This result raises a serious question of the individual and collective efficacy of these methods in the management of this complication of pregnancy.