Niphogeton ternata WILLD. ex SCHLTR. (Umbelliferae), a rare folk medicinal herb grown in Colombia, has been used for the treatment of dysentery, colitis, and rheumatism. In our search for pharmacologically active compounds from crude drugs of plant origin, we have begun to study the chemical constituents of Niphogeton ternata. Two coumarins and one polyacetylene, 5-O-(3-chloro-2-hydroxy-3-methylbutyl)-8-methoxypsoralen (1), 29,39-dihydro-jatamansin (2), and 10-chloro-1-heptadecene-4,6-diyne-3,8,9-triol (3), along with 15 known compounds (4—18), were isolated from the ethyl acetate-soluble fraction of the methanol extract of N. ternata. Their structures were elucidated by spectroscopy.