Abstract
Swiss albino mice were injected, intraperitoneally, with hydatid cyst fluid (HCF) of sheep origin and its toxin fractions (TFs) at two concentrations (10 and 50 µg/ml). changes in the wight and organ index of liver, spleen and lumph nodes, in addition to the histopathological changes occurred in these organs, and was investigated. Results demonstrate that the severity of the pathologicl lesions caused by TFs, at both concentrations, is more than that caused by HCF.