Primiparas with hypertension first recognized in pregnancy and an age- and parity-matched control group, normotensive throughout pregnancy, were monitored during 5-6 years with blood pressure recordings performed in a standardized way. At the end of the study period, 21 out of 49 women with hypertension in pregnancy had developed hypertension requiring therapy or borderline hypertension, compared with 2 women in the control group who had developed borderline hypertension. Therapy was required in 7 of the women. Factors associated with increased risk of developing hypertension were gestational week at diagnosis of gestational hypertension, 1st diastolic blood pressure during follow-up, family history, smoking, and age.