A minor, Le c blood-group inactive ceramide pentasaccharide double band fraction has been isolated from the plasma of blood group O Le(a - b - ) nonsecretors. The two purified glycolipids were analysed by NMR spectroscopy, mass spectrometry and combined gas chromatography-mass spectrometry. The following structures could be established: GlcNAc(β1 -> 3)Gal(β1 -> 4)Glc(β1 -> 1)Cer (I); Gal(β1 -> 4) [Fuc(α1 -> 3)]GlcNAc(β1 -> 3)Gal(β1 -> 4)Glc(β1 -> 1)Cer (II). It must be concluded that at least part of the secretor gene-independent plasmatic H type 2 blood-group activity can be attributed to glyco-sphingolipid I, whereas substance II, originally detected in cancerous tissue, also occurs in the plasma of healthy individuals.