The aims of this study was concerned on the evaluation the etiology of diarrhea (parasitic (E. histolytica and G. lamblia) and Celiac disease in children under five years and its effectiveness on the some laboratory investigations which is the complete blood picture (CBP), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), the sero-prevalence of celiac disease; in which two types of autoantibodies was studied, anti-gliadin (IgG and IgA), and anti-tissutransglutaminase (IgG and IgA); A total of 67 children with diarrhea have been diagnostic, E. histolytica recorded the largest group 36 sample followed by G. lamblia 23 sample, and Sero-positive celiac disease only 8 children. the E. histolytica was mostly at 4-5 years (36.1%) and G. lamblia was mostly in age 1-2 and 2-3 years (30.4%). we found that most of neutrophilia and eosinophilia cases were in E. histolytica and G. lamblia. Hemoglobin concentration show a significant decrease in patients with diarrhea. Abnormal ESR and CRP titer reading has been in shows higher mean values with E. histolytica and Sero-positive celiac disease then followed by G. lamblia.