Twenty-six primiparous women less than or equal to 25 years old who delivered between 1963 and 1978 and met the following criteria were studied: (1) The first obstetric visit was at less than or equal to 30 weeks' gestation with diastolic blood pressure less than or equal to 85 mm Hg; (2) diastolic blood pressure before delivery was greater than or equal to 95-mm Hg, rising at least 15 mm Hg; (3) 24-hour urine protein measured at least 1.0 gm; and (4) patients were enrolled in the Kaiser Health Plan in 1982. Each of the 26 patients was paired with a primiparous woman by year delivered, age, race (black versus nonblack), and weight +/- 1/3. In 23 pairs blood pressure follow-up was available in 1980 or thereafter, which was at least 3 1/2 years after delivery (average interval between delivery and follow-up = 10 years). Three in the preeclampsia group and two in the matched control group had hypertension, with diastolic blood pressure greater than or equal to 90 mm Hg. Mean systolic blood pressure (123.7 mm Hg) was 9.3 mm Hg higher in the preeclampsia group than in the matched controls (114.4 mm Hg), with a standard error of 4.15 mm Hg (p = 0.04). Mean diastolic blood pressure (77.0 mm Hg) was 2.9 mm Hg higher in the preeclampsia group than in the controls (74.1 mm Hg), with a standard error of 3.0 mm Hg (p = 0.345). We conclude that no significant difference in frequency of hypertension or diastolic blood pressure and a small but significant difference in systolic blood pressure is shown in follow-up between patients with preeclampsia and matched controls.