The Congo River basin is the second largest drainage system in the world, preceded only by the Amazon in South America. At present, about 1000 valid fish species are known from its drainage (excluding the endemics from lakes Tanganyika and Kivu), but many questions remain on the distribution of this rich ichthyofauna. This study focusses on the distribution of the relatively well-known catfishes, which are represented in the study area by just over 200 species. In a first step, the vast Congo basin was subdivided into ichthyogeographically meaningful subbasins, based on environmental and geographic parameters. This exercise resulted in the delineation of 29 subbasins for the Congo River basin sensu stricto, between its source and estuary, and an additional four for lakes Tanganyika and Kivu and their drainages. In a second step, the distribution of the catfishes of the Congo basin sensu stricto was mapped and analysed using the new subbasins. Mapping was based on the most important museum collection records of African fishes, localities from reliable literature sources and recent revisions, which were used to update distributions from collection records. This resulted in a data matrix with presence data for all catfishes in the various subbasins of the Congo basin sensu stricto. About three quarters of the studied catfish were found to be endemic to the Congo River system. One third was found to be restricted to a single subbasin. Endemic species richness varied between 0 and 12, or up to a maximum of 18.2% of the total catfish species in a subbasin. The number of species per subbasin varied from 8 to 81. Distribution patterns of individual species showed to be very variable, with relatively few species occurring throughout the Congo basin. In addition, some subbasins appeared to be characterized by a rather unique combination of species.