Background: Intestinal parasites are among the most common heath problems in most of the countries. Since it could be asymptomatic and also with respect to the role of environmental factors in this regard, the present study was conducted in Iran in the form of a national survey "health and disease" to determine the prevalence of intestinal parasites.Materials and methods: It was a cross sectional study. 1097 urban clusters (8776 families) and 590 rural clusters (4720 families) were selected through a random sampling. Stool exam was performed for subjects aged 2 years or above and the following intestinal parasites were examined: ascaris, giardia, entamoeba hystolitica, ancylostoma, taenia, tricocephal, etc. Then, the role of sex, age and site of infection was determined.Results: Of 53995 samples, 45128 samples were studies among which 45.8% were for males and 61% belonged to urban residents. Totally, 19.3% of the samples were infected where the infection rate was 19.7% in males and 19.1% in females. Giardia (10.9%) and ascaris (1.5%) were the most common protozoa and helminthes, respectively. Infection was revealed in 25.5% of subjects aged <25 years and 11.6% of subjects aged >70 years (p<0.000). Urban residents have lesser infectious disease Assistant professor, compared to rural residents (16.4% vs. 24.3%, p<0.000).Conclusion: Intestinal infection is quite common in Iran. With respect to its known side effects, the true etiology should be specified and preventive and therapeutic approaches should be considered.