Parasitic gastroenteritis is considered as one of the major threats for sheep production in Egypt. (Zaki, 1960). More than fifteen helminths species inhabit the aboma- sum and intestines of sheep were incriminated by many workers as the main cause of the disease. Among them, Haemonchus contortus, Trichostrongylus spp, Ostertagia spp. Strongyloides Papillosus, Bunstomum spp, Овво- phagostomum venulosum and Trichuris ovis were the common contributors, (Petrovic et al., 1960, Tawfik and Hassan, 1979 and Deghedy, 1981). Although, biological control may represents the ultimate goal in minimizing the detrimental effects of para- sites, practical control today requires the use of anthelmintics. Benzimidazole derivatives have been recorded by many workers as an ideal anthelmintics with a wide spectrum activity against mature and immature stages of gastrointestinal nematodes of sheep. Thiabendazole, fenbendazole and oxfendazole have been used with more than 96 percent efficacy against almost species of Trichostrongylids except Trichusovis, (Gordon, 1962, Ross, 1975, Bezubic et al., 1978, Michael et al., 1979, Ibrahim et al., 1986 and Herbert and Probert, 1987). Moreover, ivermectin either orally or parenterally reduced the faecal egg count and parasites burden with more than 99 percent activity including the benzimidazole resistant species, (Lindseg and Bulter, 1983, and Dorchils et al., 1986). Therefore, the present work was carried out to investigate the prevalence of parasitic gastroenteritis among sheep, the clinical aspects and to evaluate the antiparasitic activity of some anthelmintics as well as the hemogram and some serum constituents before and after therapy.