Extracts from the roots of <i>Paullinia pinnata</i> L. are used in West Africa as traditional remedies for a variety of diseases including infestations with soil-transmitted helminths. Based on the results of an ethnopharmacological survey in Ghana, an aqueous acetone (70%) extract was investigated for its anthelmintic and phytochemical properties. Partitioning of the crude extract followed by several fractionation steps of the ethyl acetate phase using Sephadex<sup></sup> LH-20, fast centrifugal partition chromatography, RP-18-MPLC and HPLC led to isolation of six oligomeric A-type procyanidins (<b>1</b> to <b>6</b>). To determine the anthelmintic activity, the crude extract, fractions and isolated compounds were tested in vitro against the model organism <i>Caenorhabditis elegans</i>. A significantly better activity was observed for the trimeric A-type procyanidin (<b>1</b>) compared to a B-type trimer. However, this effect could not be generalized for the tetrameric procyanidins, for which the type of the interflavan-linkage (46 vs. 48) had the greatest impact on the bioactivity. Besides the procyanidins, three novel compounds, isofraxidin-7-<i>O-</i>-l-rhamnopyranosyl-(16')--d-glucopyranoside (<b>17</b>), 4-methoxycatechol-2-<i>O</i>-(5''-<i>O</i>-vanilloyl--apiofuranosyl)-(1''2')--glucopyranoside (<b>18</b>) and a 6-(3-methoxy-4-hydroxyphenyl)-hexane-2,4-
diol-2-<i>O</i>-hexoside (<b>19</b>) were isolated together with further ten known compounds (<b>7</b> to <b>16</b>), mainly coumarins and coumarinolignans. Except for 3--d-glucopyranosyloxy-4-methyl-2(5<i>H</i>)-furanone (<b>15</b>), none of the isolated compounds has previously been described for <i>P. pinnata</i>. The anthelmintic activity was attributed to the presence of procyanidins, but not to any of the other compound classes. In summary, the findings rationalize the traditional use of <i>P. pinnata</i> root extracts as anthelmintic remedies.