Diverse forms of cell death have initially been described thanks to their observation at the electron microscope. Morphological and ultrastructural features of necrosis, apoptosis, and autophagy, considered here as prototypic cell death processes, allow one to characterize and quantify early and late cytopathological changes occurring in cells undergoing degeneration. Both light microscopy and scanning electron microscopy can provide useful insights, for example, to quantitatively evaluate cell death or to characterize cell surface changes of the cells, respectively. However, transmission electron microscopy preparation allows distinguishing among different forms of cell death. This chapter describes in brief the methods used to characterize cell death forms, including membrane, nucleus, and organelle changes, and shows paradigmatic micrographs. In particular, morphogenetic changes occurring in mitochondria during apoptosis, that is, fission process or, conversely, vacuole formation during autophagy, are shown. Possible artifacts are also described. Ultrastructural analysis seems still to provide essential information for studies on cell death.