Summary :Giardiosis is one of the most frequent parasites of dogs and cats. Since several years, the treatment is based on the use of metronidazole. A coproscopic study in four dog kennels was conducted to demonstrate, at a significant level, the efficacy of oxfendazole (Dolthène®, Merial). At the posology of 11.3 mg/kg each day during three days (D1, D2 and D3), no dogs eliminated Giardia cysts and all dogs are clinically cured. The importance of hygienic measures is underlined. In kennels 1 and 2 where hygienic conditions were poor, dogs reexcreted cysts again after treatment. In kennels where the boxes were disinfected, no dogs, treated with 22.6 or 1 1 .3 mg/kg, reexcreted Giardia cysts.