Clinical and sub clinical parasite infection depresses live-weight gain, feed intake, milk and wool production and can impair soft tissue deposition and skeletal growth. To date these infections have been controlled using anthelmintics, however the increasing prevalence of multiple anthelmintic resistance points towards the urgent need for alternative methods to reduce our reliance upon chemoprophylaxis. In addition, the worldwide growth of organic agriculture, in which the use of synthetic products is strongly restricted, needs alternatives for helminthes control. The aim of this experiment was to evaluate the effect of dietary condensed tannins (CT) on Haemonchus contortus infection in sheep.