Descriptive, illustrated keys to the world's Myxomycetes is a monograph written by the Duch naturalist Neeltje Elizabeth (Elly) Nannenga-Bremekamp (1916-1996), considered to be one of the century's researchers who contributed most to the knowledge of the taxonomy of these organisms. The book, unpublished until now, summarizes and serves as a guide for all the species of Myxomycetes recognized in the world up to the year 1996. It is an extensive and monumental project that the autor had worked on for the last 10 years of her life, and had almost finished when she died. The book provides an authoritative source of information for students, researchers and amateur naturalists interested in the taxonomy of these organisms, and it also has valuable information for protistologists, mycologists and experts in biodiversity. Written in a concise and clear language, along with many original drawings made by the author herself, it allows the identification, by means of dichotomous keys, of the more than 1000 species and varieties of myxomycetes recognized in the world up to the end of the 20th century. The manuscript was retrieved by Carlos Lado, a senior CSIC researcher who has been responsible for the revision, updating and editing of the work. He has written the foreword, where a brief biography of the author is included, and compiled lists of the 76 articles or books, and the almost 300 new taxa published by Nannenga-Bremekamp. The book is a testimony of her valuable scientific legacy and an acknowledgement and tribute to this remarkable woman, pioneer in the study of Myxomycetes.