Objective. To clarify the biomedical risk factors of preeclampsia in patients with hypertension that was present before pregnancy. Subject and methods. A clinical analysis of the course of pregnancy and labor outcomes was made in 136 pregnant women with chronic hypertension (CH) and in 83 patients with preeclampsia in the presence of CH. Clinical epidemiology methods (the relative risk (RR) and 95% confidence interval (CI)) were calculated using the OpenEpi software program) were employed. Results. The risk of preeclampsia in the pregnant women with CH was ascertained to be increased 2.2-fold if they had a family history of hypertension, 2-fold if the duration of hypertension was more than 5 years, by 2.3-fold if the body mass index was above 20 kg/m2, 1.9-fold if they were smokers; 2-fold if they were nulliparous, 2.5-fold in chronic pyelonephritis, 2-fold in chronic gastritis, 2.2-fold in Stage II hypertensive disease, 2.4-fold in grade 3 hypertension, 2.1-fold in grade IB retinal angiopathy, and 2-fold in ECG left ventricular hypertrophy. Addition of preeclampsia in the patients with CH increased the risk of premature labor 4.9-fold, including 3- and 2.8-fold at 30-35 and less than 30 weeks gestation, respectively. These pregnant women showed increases in cesarean section rates by twice and in the risk of birth of babies with asphyxia and grade III fetal growth retardation by 2.5 and 2 times, respectively; there was a 2.9-fold rise in the need for treatment of newborn infants in a neonatal intensive care unit. Conclusion. The detection of the proposed predictors for preeclampsia in pregnant women with CH will be able to identify a group of pregnant women at high risk of developing this menacing complication in order to determine their optimal management.