Scientific research in the biodiversity-rich paleotropics (the tropical portions of the Old World) provides multiple benefits, yet we know little about the distribution of research effort in this region and the factors that determine it. We used Google Scholar to assess paleotropical research effort-defined here as the number of published studies that reference one of 565 terrestrial protected areas in the 23 African and Asian countries that contain great apes (Gorilla spp, Pan spp, and Pongo spp). We found that research effort is strongly skewed toward a small number of sites and that most protected areas are inadequately represented in the scientific literature. Scientists conducting paleotropical research often focus their effor ts on protected areas that are large, that are designated as national parks, and that contain non-human great apes. Our results highlight important gaps in research effort, and indicate that current understanding of tropical protected areas is limited and heavily biased toward specific sites, many of which may not be representative of existing protected areas in the paleotropics.