Advances in fetal and neonatal medicine have resulted in an important reduction in the morbimortality due to maternal-fetal Rh blood group incompatibility. Intravascular transfusion (IVT) is the most recent change in practice. To evaluate the effect of IVT on the hematological profile of newborns. an observational, case control study was performed with Rh hemolytic disease (HD-Rh). Forty newborns were studied in 2 groups: study group (GI):20 newborns with HD-Rh, receiving IVT; and a comparison group (GII):20 newborns with HD-Rh, not receiving IVT. Cord blood samples were drawn for the following determinations: hemoglobin (Hb) concentration, venous hematocrit (Ht), platelet and reticulocyte count, lactic-dehydrogenase (LDH), total and direct bilirubin, erythropoietin (EPO) concentrations, and anti-D title. There were no differences in the Hb, Ht, total bilirubin and LDH mean values between the groups. The platelet count showed a trend to be lower in the GI(p=0.06), although in the normal range for newborns. Significantly lower reticulocyte count was found in GI compared to GII(p=0.0004), as well as the geometric mean of anti-D title(p=0.00039). The EPO concentration was higher in GI compared to GII (“t” Student, Mann-Whitney). The correlation analysis between the variables of the two groups showed: no correlation between Hb concentration and the anti-D title, negative correlation between the Hb concentration and the reticulocyte count(p=0.0007), as well as with the total bilirubin (p=0.004), direct bilirrubin(p=0.005) and LDH concentrations(p=0.01), in GII. There was no correlation between the EPO and Hb concentrations in GII, although there was in GI (p=0.03). The LDH concentration correlated positively with total (p=0.007) and direct bilirubin(p<0.0001) only in GII. The results of this study indicate that IVT changes the hematologic characteristies in newborns with HD-Rh at birth, decreasing the hemolytic rate, but not suppressing it. The reticulocyte count and the LDH concentration are probably more reliable indicators of the hemolytic process than EPO concentration at birth.* Supported by Biosintética Laboratory.