This third and last volume of the Keys to the Trematoda is the culmination of a major collaborative publishing effort providing a much needed update on the Systema Helminthum Volume 1 by S. Yamaguti published in 1958. That this has required the contributions of 18 taxonomists, for this volume alone, is testament to the prodigious effort of Professor Yamaguti. These new volumes will be the primary source of information on the taxonomy of the Digenea for coming generations but, as the editors warn, revisions to the proposed taxonomic groupings will become necessary as new molecular data reveal relationships not currently recognized from parasite morphology alone. With the publication of this volume we now have a key to all the superfamilies described, including the five in this final volume. These are the Gorgoderoidea, Microphalloidea, Monorchioidea, Opisthorchioidea, and the remaining Plagiorchioidea. Some of the taxonomic relationships presented in this new text are based on molecular data but many are not. In common with earlier volumes, contributors provide keys to determine specimens to genus, via family and sub-family, and drawings supplement the description of each genus. The book has a well-managed feel to it as the editors have imposed a comparatively uniform style so that the chapters run seamlessly from beginning to end. One editor, Rod Bray, has also introduced each superfamily before it is presented, providing useful context to each section. There is an index to all the genera and suprageneric categories, but the proposed glossary is not included because of limitations on space. This is unfortunate as inexperienced users may struggle with some of the terminology. Equally unfortunate is the tendency to omit size ranges for genera. This is not uniform but frequent enough that users will not have access to the size ranges of most genera. Diagrams (some of which are highly schematic) do not have scale bars and a few are reminiscent of the poorer attempts by undergraduate students to reproduce images from microscope slides. It would not have been an onerous task to standardize the graphical presentation of specimens in what is otherwise a well-organized, and attractively produced, text. The editors and additional contributors must be congratulated on completing this project that will provide an enduring source of information for digenean taxonomists wherever they may be. Librarians can order this volume, and the earlier volumes, in the certain knowledge that it will not be replaced or superseded in the foreseeable future.