Biochemical evaluation of the fetus using cordocentesis was performed in sixteen pregnant women with severe preeclampsia. In addition, FHR monitoring and Doppler flow velocimetry of the umbilical artery were examined in these cases before the cordocentesis. Other than blood gas and routine hematologic and biochemical examinations, catecholamine and hypoxanthine concentrations were also evaluated in some cases. According to the results it is obvious that the fetus of mother with severe preeclampsia is exposed to hypoxemia with the delta pO2, the difference from the mean in each gestation, of -22 mmHg. Especially, the prognosis of the severely growth-retarded babies with pO2 below 10 mmHg, or delta pO2 30 mmHg lower than the mean standard value, is poor. Among 16 babies, 4 with severe hypoxia or acidosis and growth retardation died perinatally. In contrast, severely growth-retarded babies without hypoxia or acidosis were alive. Since neither FHR monitoring nor Doppler velocimetry always reflect biochemical values of the fetus of a severe preeclamptic mother, hence the precise evaluation of fetal condition using cordocentesis is indispensable to determine the timing of the delivery and to prevent the neurological sequelae caused by hypoxia, especially when the fetal growth is retarded.