Bombay blood group or Hh, is a rare blood group. It is mostly found in south Asia and parts of middle East such as Iran This consists on antigen, the H antigen, this is effectively found on all RBCs. The H antigen is the building block for the production of the antigen within the ABO blood group. Normally, it is believed that the rare blood group is O negative, which is only found in selected people only. But the rarest blood group that is found in any one of millions of people is Hh blood group. This blood group was first discovered in Bombay in India by Dr. Y.M. Bhende in 1952. Anti-H has not been discovered in the ABO group, but it has been detected in the Pre transfusion Test. This H antigen works as a building block in the ABO blood group. The lack of H antigen is known as ";Bombay phenotype"; or para- Bombay phenotype. The number of H antigens present in body is 1 and the gene name is Fucosyltransferase 1. This blood group is not stored in blood banks because it is rare and its shelf life of blood is 35-42 days.