Background and Objectives: The quantification of fetal cells in the maternal circulation is an important goal to determine the amount of anti-D for prevention of active immunization of a D-negative mother giving birth to a D-positive baby. The aim of this study was to evaluate two flowcytometric staining technics for determination of fetal erythrocytes in maternal blood and to recognize the best.Materials and Methods: In this experimental study, 34 adult D-negative blood samples were spiked with six serial dilutions of D-positive cord blood (0.125, 0.25, 0.5, 1, 5 and 10%) which was representative of 99.9% of the clinical fetomaternal hemorrhage (FMH); they were stained for flow cytometric analysis. The Fetal Cell Count Kit was used for HbF dual staining and monoclonal anti-D for RhD single staining.Results: A comparison between RhD and HbF percentages and FMH volume in spiking samples was performed. A significant correlation between two different parameters in flowcytometric percentages was observed (anti-HbF versus anti-D, r=0.897, p<0.05). FMH volume was calculated and a significant correlation between expected and observed FMHs in RhD and HbF was obtained (p<0.05, r=0.984, r=0.874). The anti-HbF flowcytometric dual staining allowed better distinction between fetal RBCs (HbF+, CA-), F cells (HbF+, CA+), and adult RBCs (HbF-, CA+). Although Rh-D showed better correlation, but higher values with the RhD in suspensions lower than 10% were noted.Conclusions: Data showed that anti-HbF labeling is significantly much more accurate than RhD labeling.Quantification of FMH using these two techniques described allows precise dosage of RhD immunoglobulin for protection against anti-D allo-immunization.