The present volume of the series "Biodiversity of Bulgaria", treating the Western Rhodope Mountains, contains 40 papers by 71 authors. It starts with a geographical outline. It includes general reviews of the Mycota (1,763 species of fungi), mosses (364 species) and algae (1,257 species, varieties and forms) of the entire Rhodopes. One paper each concerns the higher flora and the arboreal diversity of the Western Rhodopes. Most of the contributions (34) treat animal diversity, altogether considering 3,958 species of Rhizopoda, Nematoda, Oligochaeta, Acanthocephala, Cladocera, Calanoida, Copepoda, Syncarida, Amphipoda, Ephemeroptera, Coleoptera, Hymenoptera, Trichoptera, Diptera, Mollusca, Pisces, Amphibia, Reptilia, Aves, Insectivora, Rodentia, Lagomorpha and Macromammalia. For each of these higher taxa, regions and groups important for conservation, as well as endemics, relicts, protected and endangered species are outlined. The book is addressed to botanists and zoologists, conservationists, biogeographers, and all lovers of the Balkan's nature.