This book, written by two distinguished American mycologists, provides an elaborate account of the morphology and biology of all known thermophilic fungi. The authors do this in a most readable form. The book is divided into three parts. Part I includes a brief introduction and a description of the methods used for the isolation and maintenance of thermophiles. More than half of the book consists of Part II, that deals with the occurrence, morphology, cultural characteristics, taxonomy and temperature relations of the investigated fungi. Fifteen taxa are described, including four new species and three new varieties of existing species. A short diagnosis is given of every described species. Illustrations in the form of good line drawings are provided for all species. Macroscopic features of three species are illustrated by excellent colour plates. Part III is devoted to general biology and practical importance of thermophilic fungi. While this book was in the press, several new reports of thermophilic fungi came to the attention of the authors. A short account of these fungi with their references is given in the Addenda. There are a few debatable points in this very useful monograph, especially in the chapters dealing with taxonomy and nomenclature. For instance it seems rather doubtful to me that the fungus described as Torula thermophila really belongs to Torula. In the description of Thermoascus thermophilus two different species are mixed up. For the perfect stage of Penicillium duponti the authors use erroneously the invalid name Talaromyces duponti (Griffon et Maublanc) Apinis. Nevertheless this is a most notable book. Its greatest value, however, lies in the very clear descriptions, while the many references at the end of the book make this an excellent reference book. The treatment is a practical and useful one. The book is well produced on good quality paper. In view of the steadily increasing interest in thermophilic fungi there can be no question of the wide usefulness of this book.