This is not at all a textbook on clinical parasitology for medical men and rather it is an attempt to describe parasitism as an important ubiquitous way of life. For this purpose, parasite and host are described together, and the book is introduced with a brief account of a fish and its possible parasites as a model for parasite-host communities. Parasitism is defined as an intimate association between two organisms in which the dependence of the parasite on its host is a metabolic one involving the mutual exchange of chemical substances. The book is written primarily for the advanced undergraduate student who has completed at least one year of Zoology or Biology and one college course in Chemistry. The sections are written in an interesting concise way. Naturally, they are too brief to allow a full exposition of every topic raised but they abound with references to books, reviews, and papers where more detailed information can be obtained. The book is excellently illustrated with black and white line drawings which are well reproduced and easy to comprehend.