The year 1952 marked a change in the understanding about blood types. That’s when the rarest blood type in the world was discovered. Dr. Y. M. Bhende and colleagues identified this rare blood type in Bombay (now Mumbai) India. Thus its name: Bombay (hh). The major characteristic of the red blood cells of the Bombay blood group is the absence of the H antigen. In India (mostly East India), it found in 1 among every 7,000-8,000 people, whereas in other parts of the world it occurs in 1 in about 250,000. Individuals with a Bombay Blood type can donate blood to types A, B, AB, and O people. However, a person with this rare blood phenotype cannot receive blood from these A, B, AB, and O types. This can make it difficult if a blood transfusion is needed. Fortunately, for individuals who possess an uncommon blood type, a rare blood type registry does exist. More next time.