A study was conducted to determine the prevalence of intestinal parasites in children from eight schools located in Phuttamonthon District, Nakhon Prathom Province during November 2004 to December 2004. Stool samples were collected from 1920 students; age range from 7 to 12 years old, and examined for intestinal parasites by using formalin-ethyl acetate concentration technique. Of these subjects, 242 (12.6%) were infected with one or more of 10 intestinal parasitic species. In these infected subjects, 214 (11.1%) were single infections whereas 28 (1.5%) were mix infections. The most frequent parasite was Blastocystis hominis (6.2%). Other parasites were Giardia lamblia (1.7%), Entamoeba coli (1.5%), Endolimax nana (1.0%), Entamoeba histolytica (0.3%), Hookworm (0.3%), Trichuris trichiura (< 0.1%), Taenia spp. (< 0.1%), Strongyloides stercolaris (< 0.1%), and liver fluke or small intestinal fluke (Opisthorchis eggs) (< 0.1%). Prevalence of protozoan infections was significantly higher than helminth infections (p < 0.05). Between male and female, there was no significant difference in prevalence of intestinal parasitic infections (p > 0.05). The results suggest that prevention and control programme for intestinal parasites should be discussed in the design of long term use in this area.