The vegetation of the states of Mato Grosso and Mato Grosso do Sul, located in Central-Western Brazil, is undergoing rapid devastation due to escalating land use in the Cerrado Biome, and to the impact of timber companies in the Amazonian portion of Mato Grosso. Therefore, it is of extreme urgency to assess the diversity of plant and animal species present, in order to plan the appropriate measures for conservation efforts in these states. The Rubiaceae is one of the largest plant families of the area studied, and an updated list of genera and species is provided here. However, this study should be con sidered a s a wor k in pro gre ss, d ue to the scar ce kno wled ge o f the flora o f thi s area . An exten sive study of bibliography and herbarium material provided the basic information for an updated synopsis of genera and a preliminary species list of the Rubiaceae encountered in the states of Mato Grosso and Mato Grosso do Sul, with a total of 68 genera and 269 species. A key to the genera, as well as a full description, synonymy and critical literature of each genus are provided. In addition, an extensive list of synonyms from the area studied and from most of the Neotropics, is given for each species.