N-(2-[2,3-Bis-(methoxycarbonyl)-guanidino]-5-(phenylthio)-phenyl)-2-methoxyacetamide (febantel, Rintal) is a new compound which is highly active against various species of nematodes and cestodes in mice, rats, dogs, sheep and cattle. In sheep and cattle a single oral dose of 5 mg/kg resulted in an almost complete elimination of larval and adult intestinal nematodes as well as Dictyocaulus. The compound was well tolerated by all animals tested.