This monograph was written because the subject of bacterial toxins has been neglected in most textbooks. Discussions of toxins of the gram-positive bacteria occupy most of the text; these include toxins of the clostridia, the corynebacteria, the streptococci, and the staphylococci. The toxins of these organisms are generally more toxic than those of the gram-negative group, and they are capable of being neutralized and toxoids can be formed from them. The gram-negative group includes Shigella dysenteriae, Brucella, melitensis, Vibrio cholerae, the neisseriace, hemophilus pertussis, Pasteurella pestis, the Rickettsia, and the viruses. Most of these are endotoxins about which less is known. References to more than 400 published articles are given. The book is recommended to anyone interested in this subject.