Background: The Rhesus (Rh) blood group is one of the most complex blood groups in humans comprising mainly of Rh D, C, c, E and e. However, only Rh D is routinely screened for in Nigeria despite the fact that other Rh antigens are clinically significant and can cause haemolytic disease of the newborn and delayed haemolytic transfusion reactions. Aim: The aim was to determine the frequency distribution of Rh C, c, E and e blood groups among pregnant women attending antenatal clinic in Port Harcourt, Nigeria. Study Design: The study consisted of 147 apparently healthy pregnant women within the age range of 18-45 years, attending a selected Primary Healthcare Centre (Obio Cottage Hospital) in Port Harcourt. The study was carried out from January 20, 2020 to March 27, 2020. The presence of Rh C, c, E and e blood groups were investigated using Anti-C, c, E and e monoclonal antibody in the same order. Results: Rh C, c, E and e were observed in 38.09%, 100%, 17.68% and 100% in the same order. Conclusion: The study indicated dominance of Rh c and Rh e over Rh C and Rh E among the studied pregnant women. It is necessary to take into cognizance the fact that the presence of Rh C, c, E and e antigens may be the cause of some delayed transfusion reactions and haemolytic disease of the foetus and newborn. Therefore, routine antigen typing for Rh antigens may help in decreasing red blood cell allo-immunization and delayed haemolytic transfusion reaction during pregnancy.