Abstract: As part of the Nationwide Survey of Human Parasite Distribution, a rando mized study based on cluster sampling was pursued in 101 pilot sites of 26 counties/cities in Heilongjiang with a coverage of 52 131 people in 1988-1991. Altogether 17 species of parasites involving 10 species of protozoa and 7 species of helminths were exhibited, the cumulative infection rate being 17.5%. The discovered species and the infection rates were noted as: Entamoeba histolytica 0.2%, Entamoeba coli 1.0%, Entamoeba hartmanni 0.02%, Endolimax nana 0.4% , Iodamoeba buetschlii 0.07%,Giardia lamblia 0.3%, Balantidium coli 0.01%, Blastocystis hominis 0.2%, Trichomonas hominis one cases, Coccidia sp. 2 cases, Ascaris lumbricoides 10.3%, Trichuris trichiura 0.6%, Strongyloides stercoralis 0.02%, Clonorchis sinensis 1.2%, Taenia solium 0.1%,Hymenolepis nana 0.03%, Enterobius vermicularis (15 years of age)16.0%. Sex based difference did not occur. High infection rates of A. lumbricoides and E. vermicularis fell on preschool children as well as pupils and middle school students, showing 24.9% for the former species, and 22.3% for the latter. C. sinensis showed its top infection rate of 2.9% in fishermen. Prevalence of the disclosed parasites in population was fundamentally related to socioeconomic status.