The Bombay blood group is a rare blood group, phenotypes of this group lacking H antigen on the red cell membrane and have anti-H in the serum. It fails to express any A, B or H antigen on their red cells or other tissues. The existence of a human H/h genetic polymorphism was first established by Bhende et al. As first discovery in Bombay (Mumbai), in India in 1952, so the name of this rare blood group is known as Bombay blood group. People having Bombay phenotype are mostly confined to the Southeast Asia. Around 179 persons in India with a frequency of 1 in 10,000 have "Bombay Blood group". A high level of consanguinity present among the parents of the Bombay phenotype. The classic Bombay phenotype has been reported in those of Indian descendent. It is quite rare in Caucasian with an incidence of 1 in 250,000. As because in our country there is routine practice of "only forward or cell type grouping" using finger prick method by voluntary blood donors organization and various blood banks; so there is tremendous chance of misinterpretation or unexploration of this Bombay blood group. When misdiagnosed, this Bombay group can cause fatal haemolytic transfusion reaction. For this reason our suggestion is to incorporate "routine serum typing or reverse grouping confirmation" along with 'O' cell control in reverse grouping procedure in every Transfusion Medicine Department or Blood Bank or Blood Donor Centers and this practice should be mandatory to reduce the risk of fatal haemolytic transfusion reaction. In this view we will highlight the incidence, molecular biology and clinical significance of this rare and fatal blood group.