We have studied an eight-member family. Three of them presented discrepancies between red blood cell and serum tests. The red blood cells fail to react with anti-A, anti-B or anti-AB of any origin. On the other hand, serum grouping tests strongly react with group B cells and fail to react with A1 and A2 cells. Then we performed saliva and adsorption/elution studies in order to demonstrate A or H substances in saliva of secretors. We conclude that the blood belonged to an A weak group named Ael.