Carex cespitosa L. (Cyperaceae) has been traditionally regarded as widespread in Europe, being reported from most countries. However, its distribution is currently overestimated due to the ambiguous use of the name C. cespitosa, together with frequent taxonomic confusion, mainly with the closely related C. elata All. and C. nigra (L.) Reichard. We present a critical revision of the distribution of C. cespitosa in Europe W of the former USSR, based on herbarium material and literature. We confirm the presence of the species in 19 European countries, while its occurrence is considered as doubtful in another five countries. Data pertinent to the ecology and conservation status of the species in the different countries are also provided. It is considered threatened or nearly so in at least eight countries. Hybrids with C. acuta L., C. elata and C. nigra are morphologically characterized and discussed. Although chorological revisions of the European flora are commonly considered of relatively minor scientific relevance, the situation detected by our survey of C. cespitosa reveals the importance of, and need for, these basic works for the accurate knowledge of many species, especially for subsequent works on conservation biology and biogeography.