Sixty-six patients with chronic hypertension were cared for during a total of 72 pregnancies. Patients were treated at home primarily by greater than or equal to 4 hours of bed rest daily in the left recumbent position. Only patients whose diastolic blood pressures remained greater than 110 mmHg were treated with hydralazine (Apresoline, Ciba). With this plan of treatment there were only 3 perinatal deaths for an uncorrected perinatal mortality of 4.1% (1.4% corrected). Twenty-nine percent of the patients had babies that were small for gestational age, 13.8% had positive oxytocin challenge tests, and 36.8% developed superimposed preeclampsia. When compared with the outcome of previous pregnancies, the program of bed rest lowered perinatal mortality from 16.8 to 8.8%. Thus, it is suggested that bed rest together with the avoidance of diuretics and the judicious use of hydralazine results in the most favorable fetal outcome.