Abstract
Background and Objectives
Rh blood group system is one of the complex systems of blood groups and composed of nearly 50 antigens. The two gens of Rh D and Rh CE are responsible for coding of Rh system. Rh null genotype does not express any of these antigens. The prevalence of phenotype Rh null is 1 person per every 6×106 individuals and it is rather difficult to find compatible blood for the recipients in need. However, as there are probably members with similar characteristics in a given family, it would be plausible to diagnose the phenotype in family members to prepare compatible blood in time of need.
 
Case
In 2014, a 39-year-old negative female patient with hemolytic anemia referred to BoAli Hospital in Qazvin. Her sample, due to incompatibility in cross matching was further tested and her Rh null group was determined.
 
Conclusions 
This case was identified by antibody screening tests and the subsequent determination of Rh antigen phenotype. After checking other family members, her brother was identified as the second Rh null group case in the country.