Gastrointestinal nematode parasitism is arguably the most serious constraint affecting sheep production worldwide. The nematode of particular concern is Haemonchus contortus, which can cause severe blood loss resulting in anemia, anorexia, depression, loss of condition, and eventual death. In this study the haematology and histopathology of different glands randomly selected sheep was studied after collection of blood and tissue sample from industrial slaughter houses in Ilam. Different regions of alimentary tract of the 375 animals were checked for the type of parasites present. Those animal with parasite consider as infected and without parasite concerned as a control The present study researched to know the species of parasite affected sheep at Ilam province having 465 Km border-line with Iraq country, in addition to study the pathological lesions in some immune system tissue glands. Dominent infection found in sheep were Haemonchus contourtus Trichurous, globulosa,Tristrongylus, colubriformis, Bunostomom trigonocephalum, Ostertagia ostertagi and sometime trematodes were also found .Erythrocyte number were significantly reduced in infected sheep. Haemoglobin concentration was also found droped in infected animal. Mean cell haemoglobin and Mean cell haemoglobin concentration did not show significant decrease while packed cell volume was significantly reduced in infected animal. Total leukocyte showed consistent pattern of increase in infected sheep percentage count of Neutrophil appear to be reduced with an evident increase in Lymphocytes. Results of this study illustrated that clinical signs of infected animals showed emaciation, sunken eye, and diarrhea, due to infection with Nematode which was identified based on the morphology of the adult worms. Histopathological findings of tissues of infected sheep particularly lymph node, revealed lymphadenitis, while in mesentery cross section of adult parasites in lumen of vein associated with thrombophelebitis has been seen, liver also showed minute granulomas around central vein. These results signify immunopathological response of the host.