The five subjects covered in this volume are Giardia and Giardiasis by E. A. Meyer and S. Radulescu; Babesiosis: Nonspecific Resistance, Immunological Factors and Pathogenesis by D. Zwart and D. W. Brocklesby; The Epidemiology of Babesial Infections by L. P. Joyner and J. Donnelly; Seasonal Occurrence of Helminths in Freshwater Fishes, Part II Trematoda by J. C. Chubb; and Hookworm infection in man by T. A. Miller. In their section of Giardia, Meyer and Radulescu discuss past as well as the most recent work on aspects such as nomenclature, morphology together with structure and function, cultivation, experimental infections, pathogenesis, human infection, immunology, diagnosis, treatment, epidemiology and their hypothesis regarding asymptomatic and symptomatic infection in humans. The photographs in the four figures are of good quality and very informative with respect to Giardia, a parasite which has provoked controversy with respect to its pathogenicity.These authors are of the opinion that Giardia infection may be present without overt clinical symptoms or it may produce disease; such a conception was given in 1926 by Wenyon in his Protozoology in which he compared Giardia intestinalis infection with Entamoeba histolytica infection.