Abstract: The genus Stylosanthes Sw ., the excellent tropical and subtropical legume forage system, consists of approximately 50 diploid or polyploid species and a common number of basic chromosomes (x =10). Five species of this genus, S. guianensis Sw., S. hamata (L.) Taub., S. scabra Vog., S. humilis Kunth and S. seabrana B. L. Maass & 't Mannetje, are the most widely planted. Because Stylosanthes has high yield, is nutrient rich, is easy to plant and has multiple purposes (e.g., for barley feed, seasoning for hay or hay powder, planting in pastures, intercropping with fruit trees, soil and water conservation and green manure), the genus has been used for agricultural production in tropical and subtropical regions of many countries, including China, India, Thailand, Malaysia, Australia, the United States, Colombia, Brazil, Cuba, and Nigeria. This review describes research advances in the germplasm resources of Stylosanthes in terms of biological characteristics, distribution, phylogenetic relationships, collection, evaluation, utilization, breeding and genetic diversity and discusses prospects of the research and several problems demanding prompt solution in Stylosanthes.