Introduction: Hereditary differences in RhD antigen expression on red cell membrane are designated as D variants. The carriers of some D variants are prone to RhD immunization. Anti-D is the leading cause of hemolytic disease of fetus and newborn (HDFN). Different D variants give different reactivities with monoclonal anti-D reagents. This can lead to immunization events, as they could be mistakenly recognized as RhD positive. Aims: To evaluate the occurrence of RhD immunization in pregnant carriers of D variants, as well as the occurrence of HDFN in their RhD positive infants. To analyze D variants detected in routine D typing using monoclonal anti-D reagents by performing extensive serologic analysis and RHD genotyping. To determine the prevalence of D variants among pregnant women of Split-dalmatian County. The overall aim of the research is to determine if it is possible to successfully use routine serologic methods for recognizing those D variant carriers that are in the risk of immunization, and by this to prevent HDFN. Methods: Two independent researches have been conducted. For Study 1, the data were retrospectively collected on the number of pregnancies in which RhD antigen was determined, the algorithm of RhD antigen typing, the RhD immunization events, HDFN occurrences and their outcomes in pregnant women over a period of twenty years. For Study 2, over a period of nine years we analyzed the samples of primiparous women which failed to show strong reactions (4+) with anti-D reagents, but were graded 3+ or less instead. Their RhD status was considered undetermined, and they underwent extensive serologic evaluation of RhD antigen in direct and indirect agglutination, as well as RHD genotyping. Results: Study 1 included 10.982 pregnancies. RhD immunization was detected in 184 pregnant women, out of which three were partial D variant carriers (one DNB, two DVa variants), which accounts for 1.63% of all RhD immunizations (CI 0.34;4.69). All three women were initially designated RhD positive status. There were no cases of severe HDFN. Study 2 included 20,851 primiparous women. Ninety-six of them (0.46%) gave weak agglutination reactions in routine serologic typing. RHD genotyping showed 73 of them (0,35%; CI 0.27;0.44) to be weak D types 1 or weak D type 3, with one case being weak D type 29. Fourteen women (0.06%; CI 0.03;0.11) were genotyped as partial D variant DVa. Genotyping was unable to specify a D variant for two women. The remaining seven women were resolved as RHD positive. The prevalence of D variants detected by serologic methods among primiparous women in our population is 0.42% (95% CI 0.34;0.52). The most prevalent partial D variant is category DVa. All DVa carriers were correctly recognized as probable partial D variants on their initial RhD typing, due to the strong positive agglutination reactions with cell line D7B8 and weak reactions (score 2+ or less) with cell line RUM- 1. Conclusion. RhD immunization occurred in three pregnant carriers of partial D antigen. There were no cases of severe HDFN in their children. The most significant partial D variant in our population is category DVa. Monoclonal anti-D reagents for testing pregnant women and transfusion recipients should be chosen in a way that will ensure that they give negative or weak positive reactions with DVa variant, such as cell line RUM-1. This will ensure that these individuals are assigned RhD negative status.