The second volume of the monograph series Fungi of Bulgaria deals with the fungi of Peronosporales (downy mildews) in Bulgaria. The monograph treats 138 species. The introductory chapter provides historical data about the investigations of that taxonomic group in Bulgaria and general information on its biology. The main body of the book consists of a key to the genera of downy mildews and descriptions of genera and species, including keys to the species of each particular genus if more than one species is found in Bulgaria. Each species description includes nomenclatural data, macroscopic and microscopic morphological features, list of the hosts, and distribution in Bulgaria. A host-fungus index and list of fungi are supplemented. Fifty-seven tables with illustrations are provided.