Two minor saponins obtained from the methanolic extract of the leaves of Ilex paraguariensis have been characterised by C-13-NMR, H-1-NMR, API-MS and chemical hydrolysis as oleanolic acid-3-O-(beta -D-glucopyranosyl-(1 --> 3)-alpha -L-arabinopyranosyl)-(28 --> 1)-beta -D-glucopyranosyl ester (guaiacin B) and oleanolic acid-3-O-(beta -D-glucopyranosyl-(1 --> 3)-alpha -L-rhamnopyranosyl-(1 -->2) }-alpha -L-arabinopyranosyl) (28 --> 1)-beta -D-glucopyranosyl ester (nudicaucin C). Both are isomeric forms of the known matesaponins 1 (MSP 1) and 2 (MSP 2) and differ only by the nature of the aglycone: they have oleanolic acid instead of ursolic acid, as found in the matesaponins. These minor saponins have not been fully separated from their major isomers MSP 1 and 2 and were characterised by in-mixture NMR analysis, LC-MS and LC-MSn experiments.