Our aim was to assess the effect of the introduction of a day-care unit on the care of women with non-proteinuric hypertension in pregnancy. A randomised controlled trial was carried out on 54 women who presented at 26 weeks of pregnancy or later with non-proteinuric hypertension (systolic blood pressure 150-170 mm Hg and/or diastolic pressure 90-105 mm Hg on two occasions at least 15 min apart). 30 women were allocated to care by the day unit and 24 were managed according to the established practice of their clinicians without access to the day unit (control group). Women in the control group spent on average 4·6 times longer as inpatients (difference in mean stay 4·0 days [95% confidence interval 2·1-5·9 days]) than the day-unit group and were 8·8 times (95% Cl 3·0-25·8) more likely to be admitted to hospital. Induction of labour was 4·9 times (95% Cl 1·6-13·8) more likely in the control than in the day-unit group and the development of proteinuria 11·4 times (95% Cl 1·8-71·4) more likely. The control group had a mean of 1·5 fewer hospital outpatient visits (95% Cl 0·36-2·64). The groups did not differ in their use of antihypertensive drugs. Day-unit care for hypertension in pregnancy significantly reduced the need for and the length of antenatal inpatient admissions and the number of medical interventions, at the cost of an increase in outpatient attendances. Our results are further evidence that inpatient care does not improve outcomes or prevent the development of proteinuria in this disorder.