Recently, Salmonella hadar has been isolated and identified from goat in Iraq. The purpose of the present study was to examine ultrastructural changes in the ileum epithelial cells of BALB/c mice experimentally infected with S. hadar. Mice were used as follows: Group A: 20 mice inoculated orally with phosphate buffer saline and considered as a control group. Group B: 20 mice inoculated orally with (100ID) by drenching the mice about 1 ml of the bacterial suspension which contain (1.5×109 cells) of Salmonella hadar and the ileum epithelial cells were examined by transmission electron microscopy at 24, 48, 72, 96 and 120 hours after infection. The ultra structural changes seen in the ileum of infected mouse at 24 hours were disorganization of the microvilli with severe cytoplasmic vacuolization, enlargement of the mitochondria and presence of intracellular Salmonella. Changes at 48 hours post infection, were detachments of many microvilli especially at the site of bacterial entry. Similar changes were observed after 72 hours but more severe; there was marked dilatation and proliferation of the endoplasmic reticulum with cytoplasmic vacuolization of the infected enterocytes. After 96 hours there were severe cytoplasmic vacuolization with accumulation of the bacteria within phagosomes and there was marked damage to the microvilli of the ileum. After 120 hours there was hypertrophy of goblet cell and thickening of the nuclear membrane and there was several Salmonella containing vacuoles.