Background: ABO blood group was the first human blood group discovered by Landsteiner in 1900.The second type of blood group is the Rhesus system.

Objective: To study the distribution of ABO blood groups and Rh types among blood donors in GMC and ESIhospital, Coimbatore and compare it with other regions of India and all over the world.

Materials and methods:A cross sectional study was carried out on 3857 healthy donor population for a period of 5 years.ABO and Rh(D) blood grouping was performed in all the blood samples collected from the donors. Data on the frequency ofABO & Rh(D) were reported.

Results: The study results were Ogroup [35%]Bgroup [33%], Agroup [22%]and AB group [10%]. TheRh–positive type [93%] Rh–negative type [7%].

Conclusion: The study depicts the frequency of blood groups in Coimbatore district population and helps to prepare donor inventory in blood banks.