Serum samples from 245 apes (184 Pan troglodytes, five Pan paniscus, 28 Gorilla gorilla, 23 Pongo pygmaeus abelei, and five Pongo pygmaeus pygmaeus) were tested for G1m (1,2,3,17), G2m (23), and G3m (5,6,10,11,13,14,15,16,21,24,28) immunoglobulin allotypes by the classical method of inhibition of hemagglutination. Some phenotypes are species specific while a few are shared by man and African apes.