Haptoglobin and red cell acid phosphatase phenotypes of Galago crassicaudatus crassicaudatus and G. c. argentatus were determined by starch-gel electrophoresis. In samples of plasma from 55 animals, a single haptoglobin phenotype, with a pattern similar to human Hp 1–1, was found. In red cell hemolysates of 55 animals, three different acid phosphatase phenotypes were distinguished. It is probable that red cell acid phosphatases of G. crassicaudatus are the products of non-dominant autosomal alleles. The enzymatic activity of red cell acid phosphatase of G. crassicaudatus wascompared with the activity of human enzyme; hemolysates from Galago have two to three times the activity of hemolysates prepared from human bloo