Introducing artificial antigens (trisaccharide-albumin complexes for A, B and H activities) as reference substances for immunoassay, blood group substances, A, B, and H in human saliva were measured. A good correlation between hemagglutination inhibition titers and concentrations of A, B, and H in saliva was demonstrated. Since the anti-H 1E3 used showed the specificity for both H type 1 and H type 2 chains and anti-H 224 for H type 2 chain, we measured H type (1 and 2) and H type 2 separately, and found 10- to 20-fold higher concentration of H type (1 and 2) compared with that of H type 2 in human saliva. The H type 2 was not found in all the saliva samples from nonsecretors irrespective of ABO subtypes. The results suggest that about 90% of A and B blood group substances in human saliva is also type 1 chain.