Blood group antigens are macromolecules attached to different components of the red cell membrane. They persist throughout life and therefore serve as identity markers. A total of 30 blood group systems are recognized by the International Society of Blood Transfusion (ISBT), some of which are not clinically significant. Clinically significant red cell antigens are those whose antibodies are capable of reacting at body temperature leading to accelerated cell destruction. They include the ABO, Rh, Kell, Kidd and Duffy antigens. Only the A, B and Rh’D’ antigens are routinely tested for in most blood banks in the country. Allo-immunization to red cell antigens contribute to morbidity and mortality in transfused persons. The frequency of the clinically significant red cell antigens and antibodies in a given population determines the availability of compatible blood units for transfusion. Knowledge of blood group cell system is also of biochemical, genetic, immunologic, obstetric, pathologic and forensic interest. Objective 1 The frequency of the A, B, D, C, c, E, e, K, Jka, Jkb, Fya, Fyb antigens in the blood donor population and their likelihood of causing Haemolytic Transfusion Reaction (HTR) and Haemolytic Disease of the New born (HDN) was determined. Methodology A total of 350 blood donors were tested. A pre-tested questionnaire was used to collect information on the socio-demographic characteristic and blood donation pattern of it subject. Data derived from the study was subjected to both descriptive and inferential statistics using Epi-info version 6.0 with statistical significance set at 0.05. Serological method was used for the determination of the frequency of red cell antigens. The A, B and D antigens were tested using the tube technique. The Rh (C, c, E, e), Kell (K), Kidd (JKa, JKb) and Duffy (Fya, Fyb) was determined by the gel column technique.