The fifth edition of this book was issued in September 1946 and reprinted in the United States in January 1948. The book is an outline of the medical aspects of bacteriology and therefore is not documented with references to the original literature. Obsolete material has been removed and an attempt made to bring the subject material up to date. Although a section on penicillin is included, no mention is made of streptomycin or other antibiotics. This may be explained on the basis of the revision date. This book should save much time for the medical student by avoiding controversial issues and presenting only the essential facts in the field of medical bacteriology.