The breakdown of D-galactose-containing oligosaccharides in germinating seeds is brought about by the enzyme a-galactosidase. One of the reasons that so much attention has been focused on seed oligosaccharides is that higher animals do not produce a-galactosidase and so cannot digest these compounds. Thus, oligosaccharides reach the hind gut unaltered and are metabolized by microorganisms. The gaseous by-products of this metabolism give rise to flatulence, which causes discomfort to domestic animals and humans alike. The importance of oligosaccharides as anti-nutritional factors is such that, in a recent survey of the use and potential use of legume seeds as food and feed (Nwokolo and Smartt, 1996), the raffinose series of oligosacchararides received widespread attention, whereas starch, the main energy source in the seeds, was virtually ignored. The considerable genetic variation in the oligosaccharide content of seeds suggests that breeding programmes to produce seeds with low oligosaccharide content would be successful. However, evidence from studies of the role of oligosaccharides in the biology of seeds indicates that care needs to be taken to ensure that any improvement in food quality is not achieved at the expense of seed storability or seedling survival.