An original high performance liquid chromatography assay enabled the quantitation of levamisole in biological fluids of ewes (n = 4) and goats (n = 4). An open 2-compartment model showed the development of the drug in animals after oral (10 mg/kg), i.m. (7.5) and s.c. (7.5) administrations by veterinary therapeutic forms. Greater efficiency was obtained in both species after i.m. rather than s.c. or oral administrations. After i.m. injection, levamisole levels in nasal secretion and saliva were 5-20 times higher than in plasma. Because of the high susceptibility of goats to levamisole, the s.c. route is preferred in this animal.