SUMMARYChicory is a perennial crop that has been investigated as a forage source for outdoor-reared ruminants and pigs, and has been reported to have anthelmintic properties. Here, we investigatedin vitroanthelmintic effects of forage chicory-extracts against the highly prevalent swine parasitesAscaris suumandOesophagostomum dentatum.Methanol extracts were prepared and purified from two different cultivars of chicory (Spadona and Puna II). Marked differences were observed between the anthelmintic activity of extracts from the two cultivars. Spadona extracts had potent activity againstA. suumthird (L3) and fourth (L4) – stage larvae, as well asO. dentatumL4 and adults, whereas Puna II extracts had less activity againstA. suumand no activity towardsO. dentatumL4. Transmission-electron microscopy ofA. suumL4 exposed to Spadona extracts revealed only subtle changes, perhaps indicative of a specific anthelmintic effect rather than generalized toxicity. Ultra-high liquid chromatography-mass spectrometry analysis revealed that the purified extracts were rich in sesquiterpene lactones (SL), and that the SL profile differed significantly between cultivars. This is the first report of anthelmintic activity of forage chicory towards swine nematodes. Our results indicate a significant anthelmintic effect, which may possibly be related to SL composition.