Background: Baboons and monkeys fail to express ABH antigens on red blood cells (RBCs), and the A or H antigens are expressed only weakly on the surface of pig RBCs. Baboons and monkeys have been previously blood typed by detection of ABH antigens in the saliva after administration of pilocarpine. A reliable method to ABH type pigs is by immunohistochemical staining of renal distal tubules in kidney biopsies. We describe a simple and efficient method to blood type baboons, monkeys, and pigs. Methods: Baboons (n=14) and cynomolgus monkeys (n=8) were blood typed by staining of buccal mucosal smears and by determining the presence of serum anti-A or B antibodies following human type O adsorption. Pigs (n=11) were tested for ABH type by immunohistochemistry for the presence of A, B, and H antigens using monoclonal antibodies on (i) renal biopsies, (ii) RBCs, and (iii) buccal mucosal smears, without pilocarpine administration, in addition, (iv) after adsorption on human type O RBCs to remove anti-human antibodies, the pig sera were typed by hemagglutination assay for the presence of anti-A or B antibodies using human A and B RBCs. Results and conclusions: There was complete consistency among the results obtained using all of the above methods, except that no determination could be made from staining of RBCs in one pig. Staining of buccal mucosal cells proved to be the preferred method in all three species because: (i) expression of A or H antigen is weak on pig RBCs, making an accurate blood type determination difficult, and A, B, and H expression is non-existent on baboon and monkey RBCs, (ii) neither venepuncture nor organ biopsy is necessary, (iii) time-consuming adsorption of anti-human antibodies from the sera of the test animal is not required, and (iv) it proved a quick method of evaluation. © Blackwell Munksgaard, 2006.