The article presents some studies on study of some aspects of pathogenesis in associative parasitosis of gas-trointestinal tract of sheep. As a result of the conducted studies, it was found that during spontaneous invasion of sheep by associations of parasites of gastrointestinal tract, following changes were established: a significant decrease in number of red blood cells by 1,77 times (P<0,001), hemoglobin-by 39,86 % (P<0,001), an increase in alanineaminotransferase and aspartateaminotransferase – by 1,59 times (P<0,01) and 1,42 times (P<0,001), alkaline phosphatase – by 1,32 times (P<0,001).
