1. 1. The metabolism of glucose-C14 in a pathogenic strain of Leishmania brasiliensis is studied. 2. 2. A significant amount of C14O2 was evolved when incubated with glucose-1-C14 as compared with that evolved from glucose-6-C14. 3. 3. A large amount of radioactivity from uniformly labeled glucose is incorporated into volatile organic acids. 4. 4. The significance of the pentose cycle in various trypanosomes is discussed. © 1969.