**Abstract**

In this chapter, we summarize the highlights of the early events in the interaction of parasitic protists and the host cell. Pathogenic protists are a group of eukaryotic organisms, responsible for causing different human diseases, such as malaria, Chagas disease, leishmaniasis, and toxoplasmosis. These pathogens display complex life cycles and go through different cellular transformations to adapt to the different hosts in which they live. Part of these life cycles takes place in mammals, inside the host cell. Host cell entry ends with the formation of phagosomes or parasitophorous vacuoles, which differ from each parasite and each type of host cell. While canonical phagocytosis involves the fusion of phagosomes with compartments of the endocytic pathway to produce normal maturation through the phagocytic route, pathogenic microorganisms have developed Different evasion mechanisms to resist the intracellular defense systems. These strategies, including phagosome maturation arrest, resistance to the harsh lysosomal environment, or exit to the host cell cytoplasm, will be also presented in this work.

**Keywords:** phagocytosis, parasitophorous vacuoles, phagosomes, pathogenic protists, parasites
