Background: Intestinal parasites are one of the most significant health issues affecting primary school children. They are usually associated with poor personal hygiene and contaminated water or food. They cause symptoms including abdominal pain, chronic diarrhea, loss of appetite, and anemia resulting from malabsorption. Recurrent infections also negatively impact children's physical and cognitive development, impairing their academic achievement. Aim: The present study aimed to estimate the overall prevalence of parasites and identify the most common species, as well as to identify risk factors (water, hygiene, handwashing behaviors, animal husbandry), and to compare prevalence by sex and age group. Method: Schools, classes, and students were randomly selected from schools in Najaf to ensure a fair representation of the sample. Data was collected using a structured questionnaire that included demographic information, hygiene habits, and medical history. Stool samples were collected in sterile containers with a secret code. Direct microscopy and formal-in-ether concentration (FET) were performed, and a sample was considered positive when eggs, cysts, or parasites were detected by either method. Result: The results showed that Giardia lamblia was the most common parasite, followed by Entamoeba histolytica. Also, the results of the current study showed no statistically significant relationship between water source, unhealthy behaviors, demographic factors, and intestinal infection, even though the majority of participants sourced their water from the tap and had unhealthy behaviors. However, a statistically significant relationship was found between the type of diagnosis and the incidence of chronic diseases (p < 0.001). Conclusion: Giardia lamblia was the most common intestinal parasite in the sample, with no statistically significant correlations with behavioral or demographic factors, reflecting general environmental and societal influences on its prevalence pattern. A significant association was also found between intestinal parasite infection and chronic diseases, indicating an increased susceptibility to infection in this group and the need to include them in surveillance and prevention programs.