Abstract
Bombay blood group is a rare type that was initially identified in the city of Bombay, India. It is characterized by the presence of serum antibodies anti-A, anti-B, and anti-H, which can cause agglutination in all blood groups within the ABO system. The clinical importance of the Bombay blood group lies in its inability to receive transfusions from other blood groups. In this case report, we present a case of a young male who was initially misdiagnosed as having an O phenotype, resulting in a hemolytic transfusion reaction. This case highlights the diagnostic and therapeutic challenges associated with rare blood phenotypes.