The occurrence of physiological cell death has been known for decades, but interest in the subject was renewed in 1972 when Kerr, Wyllie and Currie described in detail the ultrastructural changes characteristic of dying cells and coined the term apoptosis to describe the process. Cells display a wide variety of morphological changes when dying during development or following a toxic insult. A binary classification scheme suggests that physiologically appropriate death is due to apoptosis and that pathological mechanisms involve necrosis. However, recent studies indicate a potential involvement of apoptotic cell death in ischemia, status epilepticus and HIV-1 infection.