Diet influences the stable isotope ratios of carbon and nitrogen (δ13C and δ15N values) in animal tissue; but here we explore the influences of particular aspects of the local environment on those values in chimpanzees (Pan troglodytes). In this article we present new δ13C and δ15N values in Gombe chimpanzees using hairs collected from night nests in 1989. Then, we explore the influence of environmental factors by comparing our Gombe data to those from eight additional Pan study sites with previously published stable isotope data. We compare chimpanzee δ13Chair and δ15Nhar values to specific characteristics of local site ecology (biome and ecoregion) and to local Mean Annual Precipitation (MAP) to test hypotheses based on known effects of these variables on the δ13C and δ15N values in plant tissues. The comparison shows that hair from chimpanzees living in savanna sites with lower MAP have higher δ13Chair values than do chimpanzees living in woodland and forested sites with higher MAP. These results demonstrate the potential of using δ13C values in primate tissue to indicate aspects of their local ecology in cases where the ecology is uncertain, such as samples collected early in the last century and in fossil hominins. In contrast to expectations, however, chimpanzee δ15Nhair values from some savanna sites with lower MAP are lower, not higher, than those living in more forested areas with higher MAP. It is likely that diet selectivity by chimpanzees affects δ15Nhair values to a greater extent than does the influence of precipitation on plants.