The paper reviews basic aspects of the biology of Trypanosoma cruzi emphasizing the following topics: (a) developmental stages of the life cycle in the vertebrate and invertebrate hosts; (b) the cytoskeleton of the protozoan, especially the sub-pellicular microtubules; (c) the flagellum, emphasizing its attachment to the protozoan body through specialized junctions; (d) the kinetoplast-mitochondrion complex, describing its structural organization and the replication of the kinetoplast-DNA; (e) the peroxisome (glycosome) and its role in the metabolism of the cell; (f) the acidocalcisome, describing its morphology, biochemistry and functional role; (g) the cytostome and the endocytic pathway; (h) the organization of the endoplasmic reticulum-Golgi complex; (i) the nucleus, describing its structural organization during interphase and division, and (j) basic aspects of the process of interaction of the parasite with host cells.