The chemical composition of mature whole seeds of six cultivars of yellow lupin (Lupinus luteus L.), three cultivars of white lupin (Lupinus albus L.) and two cultivars of narrow-leaved lupin (Lupinus angustifolius L.) was determined with particular attention to the content of a-galactosides and non-starch polysaccharides. α-Galactoside contents significantly differed among lupins, averaging (per kg DM) 105, 85 and 60 g in yellow, white and narrow-leaved lupins, respectively. Stachyose was the dominant a-galactoside; its level in seeds of yellow and white lupins was similar (about 60 g) and significantly higher than in seeds of narrow-leaved lupins (about 33 g). Opposite proportions of the minor a-galactosides, galactopinitol, digalactopinitol and digalactoinositol, were observed. The highest proportion of verbascose was found in the seeds of yellow lupins. Yellow lupins seeds contained significantly less non-starch polysaccharides (321 g) than other lupins (about 400 g). Glucose and galactose constituted the main part of NSP sugar residues (from 31 to 43% and from 31 to 32%, respectively). Considerable differences among species were found in the contents of rhamnose, xylose, galactose and uronic acids.