Deforestation around large urban centers usually creates a fragmented landscape with reduced natural areas. Biodiversity studies in these forest remnants provide useful tools for designing conservation strategies that maximize the persistence of local diversity and promote their connectivity. Inventories focused on particular taxa have been proposed as a useful mechanism that allows a better knowledge of the state of biodiversity in a given area, the butterflies are one of the taxonomic groups more frequently used for these studies. In this paper, we study the diversity and composition of the butterfly community in the cloud forest of the reserve El Romeral located southwest of the Medellin City in the Aburra Valley, Colombia. We recorded 75 species belonging to 5 butterfly families, more than recorded for similar forests associated with periurban areas. El Romeral shares only 50% of the species with the main periurban forest located east of the valley, indicating that each of the surrounding forest remnants of the city may have a unique composition of species being complementary and useful for regional conservation.