Sheep production has serious problems due to the spread of intestinal parasites. These parasites cause loss of appetite, maldigestion, slow growth in body weight and wool, all of which results in economic losses as well. The control measures of infestation with strongyloid parasites in ruminants have until now been based mainly on the organization of grazing and the use of antihelmintics. However, due to the occurrence of resistance, alternative methods of control have been introduced. The use of nematophagous fungus Duddingtonia flagrans, which is capable of decreasing the number of infectious larvae and eggs in feces, has been successful. The aim of this study was to determine whether Duddingtonia flagrans decreases the number of eggs of Trichostrongylus spp in sheep feces. Fecal samples of thirty-four sheep were examined and the parasites were found in twelve sheep, six of which were fed with the fungus, and six of which were used as the control. According to χ2 test, at the level of certainty of p<0,005, a statistically important difference in the number of eggs was observed between the sheep which were given the fungus and those which were not.