Apoptosis is essential for the development and normal physiology of multicellular organisms. Why a similar form of programmed cell death might exist in single-celled organisms is less obvious. Nevertheless, there is some evidence that budding yeast can undergo a form of apoptosis – despite lacking bona fide homologues of the death-effecting proteolytic enzymes caspases. Birthe Fahrenkrog and co-workers now strengthen the case for yeast apoptosis by identifying a new component of its death machinery (see p. 115). They show that budding yeast has a homologue of mammalian HTRA2, a protease that promotes apoptosis by antagonizing the inhibitor of apoptosis (IAP) protein XIAP. They find that this homologue, Nma111p, is essential for yeast apoptosis induced by stresses such as heat or hydrogen peroxide. Moreover, it promotes apoptosis when overexpressed. The proapoptotic effects of Nma111p depend on its serine protease activity, and it aggregates in the nucleus once apoptosis is induced. The authors' findings significantly extend the parallels between yeast and mammalian apoptosis and, given the power of yeast genetics, will also provide a useful new system for analysing the function of HTRA2-like proteins.