1-Phenylhepta-1,3,5-triyne (1), 5-phenyl-2-(1′-propynyl)-thiophene (2), and 2-(3′-acetoxy- 1′-propynyl)-5-phenylthiophene (3) were isolated from Coreopsis lanceolata L., and their structures identified by spectroscopic methods. Compounds 1 and 2 showed effective nematicidal activities against Bursaphelenchus xylophilus and Caenorhabditis elegans, but had hardly any effect against Pratylenchus penetrans. Compound 3 did not show any effective nematicidal activity.