Seeking correlations between occurrence of species and environmental variables and so predicting other areas of likely occurrence is of value both to the planning of ex situ and in situ conservation and may provide a greater understanding of the spatial distribution of genetic diversity. Geographic Information Systems software is gradually becoming more widely utilized, as in studies examining the distribution of crops, wild relatives of crops and wild species. The gene pool of the genus Stylosanthes Sw. has given rises to some important cultivars grown in many regions of the world. The perennial species Stylosanthes guianensis Sw. has a wide distribution throughout South and Central America, between the latitudes 23°N lat and 27°S long. The procedures involved in estimating the distribution of a species are described using as an example Stylosanthes capitata Vog. A file containing data on 311 accessions was collated, each accession having a latitude, longitude and elevation.