Abstract: Infectious gastroenteritis is one of the most common diseases in most people . To clarify the infectious etiology of diarrhea in some patient aged from 8-30 years, we collected in clean suitable container stool samples from 78 patients with diarrhea from general teaching Hilla Hospital from September \2014 to April\2015.
From 78 diarrheal cases, only 38 (48.71%) cases are caused by bacteria and 27 (34.6 %) cases are caused by parasites , also there are 13 (16.66%) cases have mixed infection between them. Gram negative bacteria formed 76.31% (29 cases) represented by E. coli 16 cases (55.17%), Salmonella spp.6 cases (20.68%), Shigella 3 cases (10.34%), Klebsiella pneumoniae and Pseudomonas aeruginosa 2 cases (6.89%) for each one. While gram positive bacteria consists 23,68% (9ases) represented by Clostridium spp. 4 cases (44.44%), Bacillus spp. 3cases (33.33%) and Staphylococcus aureus 2cases (22.22%), while parasitic infection were Giardia lamblia appears as the most frequent parasitic causative agent 11cases (40.74 %) followed by Entamoeba histolytica 9 (33.33% ), Entrobius vermicalaris 4 (14.81%) , Hymenolips nana 3 (11.11%). Increased rate of infection were falls on the first and second age groups, and also high rate of infection were recorded in females than in males.