Hypertensive disorders during pregnancy implicate placental pathologic conditions, which may interfere with the normal passage of a-fetop rote in (AFP) to the maternal blood. We compared the levels of maternal serum (MS) in early second trimester of pregnancies complicated by hypertensive disorders with those of matched controls. The distribution in the study group of MS-AFP multiple of median values was significantly different from the distribution in the control group. Moreover, up to multiple of the median 1.00, the number of hypertensive patients was larger than the number of normo-tensive pregnant women. The mean level of multiples of the median in the study group was significantly lower than that of the control group (p value = 0.003, 95% confidence interval: -0.30, -0.05). In the analysis of the distinct types of hypertension, the difference remained significant for 85 women in the moderate hypertension subgroup (p value = 0.032, confidence interval: -0.34, -0.02) and was not significant for the severe hypertension subgroup of 22 women (p value = 0.24, 95% confidence interval: -0.57, 0.15) and chronic hypertension subgroup of women (p value = 0.52, 95% confidence interval: -0.44, 0.00). The trend was consistent in all the subgroups. Relatively low values of maternal serum AFP at early second trimester of pregnancies with hypertensive disorders may be a result of placental pathologic involvement and can help in the identification of the women at risk.