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Abstract: Serological markers have served as important indicators for the understanding of genetic variation between and within population, providing valuable insight into the dynamics of population structure. The present study, therefore aimed at providing the percentage frequency of the ABO and Rhesus distribution pattern of adults who attended the Federal Medical Centre Lokoja, Kogi State, Nigeria for record and health planning. The study was carried out on two hundred adults (77 male and 123 female). The blood samples were taken by cubital venepuncture and analysed using the agglutination method (Dacie and Lewis 2001). Among the male population; Blood group O was the highest with the percentage frequency of 22.5 %, followed by blood group A (7.5 %), B (6.5 %) and the least percentage frequency was observed in blood group AB with 2 %. Among the female population; Blood group O, A, B AB had percentage frequency of 29 %, 11.5 %, 17.5 %, and 3.5 % respectively. The RhD distribution also varies among male population; RhD positive 87 % and RhD negative 13 %. The percentage frequency of RhD positive among the female population was 93.5 % and that of RhD negative was 6.5 %. The total percentage of RhD positive was 91 % and that of RhD negative was found to b