The renal and uterine arteries of 52 patients with normal course of pregnancy and 12 patients with EPH gestosis were examined by Doppler sonography between the 35th and 38th weeks of gestation post menstruationem. Doppler curves of renal arteries were recorded in a further 31 nonpregnant subjects. A significant difference in arterial vessel resistance was found between patients with normal course of pregnancy and those with EPH gestosis. There was also a significant difference in the circulation parameters in the renal vessels between patients with normal courses of pregnancy and the nonpregnant controls. However, there were no differences in this vessel segment between the patients with EPH gestosis and the nonpregnant controls. Among patients with EPH gestosis the renal increase in resistance was relatively more pronounced than the uterine increase. In addition to the calculated flow parameters there were also marked differences in the Doppler curves of these two groups. There is evidently a considerable increase in renal circulation in normal pregnancies. This is in agreement with findings described in the literature, obtained by invasive methods. On the other hand, a clear limitation of renal and uterine resistance was seen in the patients with EPH gestosis. This ties in with the well-known morphologic changes in the kidneys in cases of EPH gestosis. A larger patient sample will have to be studied to determine whether the renal vascular changes described here may represent an early sign of EPH gestosis. If this is confirmed it would make sense to include Doppler sonography of the renal vessels in routine diagnostic procedure.