[Rhesus antagonism, sometimes different from usual]

We describe three children with an active rhesus antagonism. However, laboratory results and course were different than usual. The first child had blood-type O positive, while his mother had blood-type O positive as well. The mother of the second child had blood-type A negative, while the child seemed to be A negative too. The third child needed an exchange transfusion due to a 'regular' rhesus antagonism, but died shortly after. The mother of the first child turned out to have a rhesus D VI variant. The second child had a 'blocked' D-antigen due to excess anti-D antibodies. The illness of the third child looked like Graft versus Host disease clinically, but eventually appeared to have congenital myelofibrosis. A correct diagnosis in these children is of great importance in future pregnancies, blood transfusions and genetic counseling.