In recent years, parasitologists have learned much about the way in which parasite biochemistry differs from that of free-living organisms. Inside the host, factors such as temperature, oxygen tension, carbon dioxide concentration and pH have important consequences for the biochemistry and physiology of the parasitic organism. Strong selection pressure therefore operates at all stages of a parasite's life cycle. The parasite's adaptational response to this pressure is the subject of this book. Under the headings "The nature of parasite adaptation", "Energy metabolism", "Digestion and uptake of nutrients", "Host immunity and parasite adaptation", "Biochemical adaptation and the magic bullet" and "Biochemical variation in parasites", present knowledge of parasite metabolism and how it reflects adaptation to particular environments is surveyed. The ways in which these adaptations may have developed during their evolution - with reference to the modern evolution of strain variations and the development of resistance to antiparasitic compounds - are explored, together with immunological aspects of the host-parasite relationship and potential metabolic targets for chemotherapy. This book should be of use to all those involved and interested in the biochemistry of parasites and its relation to their evolution, ecology, adaptation and variation. Those aspects of parasite metabolism that are attacked by anti-parasitic drugs are described, making this a useful book for those involved in the pharmaceutical industry. This book should be of interest to parasitologists and comparative biochemists.