This is a good source book for experimental work conducted on oncogenic viruses. Essentially none of the important contributions in this field has been omitted. Many of the older discoveries are included, but the author has also brought the reader up to date by reviewing recent contributions in the areas of chicken leukosis, mouse leukemia, and parotid tumors. The author is to be commended particularly for including important negative experiments and for carefully documenting experimental work. The bibliography is extensive and original work well credited. It would seem that the beginner in the field of oncogenesis could start with this book to obtain the necessary background before plunging up some previously traveled path. The book represents a well-organized cross-index for workers in restricted or narrow fields of viral influences on tumors. All in all, this is good book to have available for those interested in tumors, viruses, and virus-cell interaction.