Data on the distribution of approximately 340 species of heterotrophic flagellates (protozoa) in 29 communities from sites around the world are summarized. We seek to minimize the impact of factors extrinsic to the actual distribution of organisms that may distort our perception of the geographic patchiness of organisms. In our analyses, communities from similar geographic areas do not cluster together, but communities from similar habitats do cluster together. Our insights are constrained by under-reporting and species concepts, but we favour a mode l in which there are relatively few species of heterotrophic flagellates and that most have a cosmopolitan distribution.