The glycolytic enzymes of Tritrichomonas foetus, unlike those of Trypanosoma brucei, are apparently not located in microbody-like organelles (glycosomes) but appear to occur in the cytosol. 2. The localization of the glycolytic enzymes in Crithidia fasciculata and in the epimastigote and trypomastigote forms of Trypanosoma cruzi is however similar to that in T. brucei. 3. No evidence was obtained for the existence of glycolytic enzyme-containing microbodies in rat liver. 4. The glycosome is probably an organelle unique to members of the Kinetoplastida.