An ethanol extract of aerial parts of Spigelia anthelmia was submitted to vacuum column chromatography being eluted with hexane, chloroform, ethyl acetate and methanol. The four extracts were assayed for anthelmintic activity against Haemonchus contortus, the main nematode in caprines. The ethyl acetate extract showed the strongest anthelmintic activity and the chemical study of this extract revealed as main constituents the alkaloid spiganthine and 3,7-dihydroxy-3',4'- dimethoxyflavone.