Plasma volume determinations for 9 women with severe chronic hypertension who delivered live-born infants with birth weights appropriate for gestational age (AGA) were compared with those for 7 women with chronic hypertension whose pregnancies ended in intrauterine fetal demise. Plasma volume determinations using Evans blue dye dilution technique were performed at 20 to 25 weeks' gestation (12 patients) and at 26 to 29 weeks' gestation (16 patients). In addition, plasma volume measurements were performed at 8 weeks post partum in 5 patients who had intrauterine fetal demise. Analysis of the clinical course, laboratory findings, and pregnancy outcome revealed that the degree of plasma volume expansion was the factor most significantly differing between the 2 groups of patients. The plasma volumes of 9 women who delivered AGA infants were comparable with those values previously reported for normal singleton pregnancy. In contrast, each patient with intrauterine fetal demise demonstrated failure in plasma volume expansion at 20 to 25 weeks' gestation when compared with her own postpartum value. In each of the 6 patients who had a second plasma volume determination at 26 to 29 weeks' gestation, there was a decrease (mean decrease, 13.5%) from the value at 20 to 25 weeks. Plasma volume determinations may be very helpful in making clinical decisions regarding women with severe hypertension. Plasma volume determination may be most helpful in identifying a subgroup of women who are at particular risk for having infants with intrauterine growth retardation and intrauterine fetal demise.