(Uploaded by Plazi for the Bat Literature Project) There are particularly few vertebrate studies in areas that support man's modifying action. Studies on the reproductive biology of Neotropical bats indicate that the majority reproduce seasonally. This lead us to document this behaviour at the La Molina National Agrarian University campus, located in an urban area of the city of Lima, Peru. In order to recognise the reproductive patterns of the species, bats were captured from October 1995 to September of 1996. A total of 180 individuals was captured, comprising 4 species, pertaining to the Phyllostomidae and Vespertilionidae families. The most abundant species were Glossophaga soricina and Artibeus fraterculus. For these species, bimodal polyestric patterns are reported. Results reveal that both species follow this pattern and that the females of G. soricina . and A. fraterculus have at least one post - partum estrous period per year.