Abstract: A province wide investigation on human intestinal protozoa was undertaken in 164 sites of 39 counties/cities in Henan. By using Logol's solution as stain for direct fecal smears, 17 482 (20.4%) out of 85 553 people were detected to harbor protozoa. Altogether 11 species of protozoa were discovered, among which, Giardia lamblia showed the highest infection rate (7.1%), while others revealed infection rates ranging from 0.001% ( Balantidium coli ) to 5.6% ( Endolimax nana ). Age , sex , occupation and nationality based associations with protozoan infections were analysed to see their possible relationships. The investigation actually founded a base for working out control strategies aiming at protozoan infections in the province.