BACKGROUNDParasites are a group of eukaryotic organisms. They may be free living, may form symbiotic relationships or form parasitic relationships with the hosts. The total number of recognised species of parasites are over 800,000. They may be unicellular or multicellular. Unicellular parasites include protozoa, while multicellular parasites include helminths and arthropods. The parasites are associated with human beings since the beginning of civilisation. The parasitic diseases are present worldwide including India. In addition to the already prevalent diseases, newer diseases are emerging in the clinical scenario. The systemic diseases like cysticercosis, paragonimiasis, hydatidosis and toxoplasmosis are common. Acquired toxoplasma infections are rising in incidence in immunodeficient individuals. Cestodes, trematodes, tissue flagellates and sporozoa affect human beings commonly including their eyes in different parts of the world. They thus constitute a real health problem globally. The basics of parasitology lie in morphological and pathological studies. This scope has extended further with recent updates in molecular parasitology. The present review discusses the principal ocular parasites found in India and the world with reference to microbiological and pathological aspects and gives outlines of management.