Galectins are a family of animal lectins with affinity for beta-galactosides. By using recombinant proteins, a number of galectins have been shown to interact with cell-surface and extracellular matrix glycoconjugates through lectin-carbohydrate interactions. Through this action, they can affect a variety of cellular processes, and the most extensively documented function is induction of apoptosis. By using gene transfection approaches, galectins have been shown to regulate various cellular processes, including apoptosis. Evidence has been provided that some of these functions involve binding to cytoplasmic and nuclear proteins, through protein-protein interactions, and modulation of intracellular signaling pathways. Thus, some galectins are pro-apoptotic, whereas others are anti-apoptotic; some galectins induce apoptosis by binding to cell surface glycoproteins, whereas others regulate apoptosis through interactions with intracellular proteins. This review describes involvement of galectin-1, -2, -3, -7, -8, -9, and -12 in apoptosis.