The efficacy of ivermectin against natural infection of the mange mite Sarcoptes scabiei var canis in foxes was evaluated. The investigations consisted of two field studies and one controlled study. In experiment 1, ivermectin was given as a single subcutaneous dose at 200 micrograms/kg in six foxes. In experiment 2, was one group, consisting of five animals, administered 200 micrograms ivermectin/kg s.c. twice with an interval of 35 days. Group two, consisting of four animals, was given one subcutaneous injection of 400 micrograms ivermectin/kg. In experiment 3, ten foxes were given 1 ml 0.2% Eqvalen s.c. (i.e. 340-440 micrograms ivermectin/kg). A control group of ten animals was not medicated. Before and after treatment a clinical evaluation and skin scraping for microscopic examination was carried out in all three experiments. The results indicated that ivermectin was a good alternative in the therapy of the Sarcoptes mange in foxes by moderate mite infection. A progressive clinical improvement of the mange lesions was evident in the treated foxes. Mites were not detected in skinscraping, except in one animal in experiment 3. It was concluded that ivermectin should be administered, in an initial dose of 400 micrograms/kg and a repeated dose of 200 micrograms/kg 2-3 weeks after the first treatment.