This chapter describes the most important and common blood group system in human- the ABO and Rh Blood group systems. How ABO and Rh grouping is done, how a donor is selected, what screening tests that are done prior to blood collection, how blood is collected and stored are described here. Indications of blood group analaysis and blood transfusion are also mentioned. The most important test for transfusion-‘cross matching’ (Combs test-direct and indirect) its types and how to do it, is described in details. Components of collected blood like whole blood, fresh frozen plasma, packed cell volume, platelet concentrate, buffy coat preparation and indications of their use are also discussed. Acute and chronic complications of blood transfusion, its 3 stages, investigation to be done are also written. Finally, how to set up a new blood bank including the staffs, space and equipments needed are also briefly described.