Parasites and parasitic morbidity and/or disease seem to be a birth right of the tropics. This is a sequel to greaterbiodiversity fragmented in relation to biogeography and climatic shifts congenial to nocturnal enemies of humans,like mosquitoes. In fact in some cases parasite strategies have thwarted attempts of the scientific community toeradicate them. The best example running its course now is any kind of flu. Flu is no simple single strain strategy.At the base of parasitic diseases, man has recognized a dichotomy namely, animal diseases and diseases of man butthere may be links between humans and animal (zoonoses).We owe a great deal to the British Empire in the expansion of knowledge of tropical diseases especially ofpeninsular India with more or less warm climate plenty of room for growth of intermediate host like Anopheles(malaria), Culex (filaria) and Aedes (dengue). The School of Tropical Medicine and Hygiene at London is especiallyinterested in this direction. We have at the present time many insitutions in India dealing with public health problems.Schools of Tropical Medicine, Calcutta, several laboratories of preventive medicine and more recently immunologylaboratories. Likewise, there has been a growth of institutions dealing with veterinary medicine and animal health.We are just begining to understand what is known as zoonoses. That is parasites which normally infect and developin animals can under certain circumstances infect humans and thrive with as much ease. India can now boast ofbeing free of smallpox and plague but bad hygienic conditions are not allowing the control of malaria, dengue,filaria, typhoid, leprosy, etc. Dilution of efforts because of population explosion is the cause. A multiprolongedattack 1. Treatment, 2. Eradication of intermediate hosts (like mosquitoes) 3. Preventive measures (Prophylaxis)specific to each parasitic infection becomes a must, education is necessary.The aim of the present books is to provide a brief but reasonably comprehensive information to the medicalstudent as well as students of medical laboratory techniques. To be a comprehensive parasitologist of some worthand meaning the persent book has been designed. Equal emphasis is given to microbes and the protozoan andmetazoan parasites. Two pertinent remarks can be quoted. Stoll 1947” had said that at any army center the medicalorricer never heard of bancroftian filariasis (the disease) while soldiers saw it with dismay elephantiasis (thesymptom) Philip 1987 had said that there is always some thing new under the parasitological sun.