Abstract: Nanyang Basin is the largest basin in Henan Province. Owing to its special topography, the mean temperature in the Basin is the highest in Henan. Undoubtedly it is also the locality with the highest prevalence of human parasitic infections in the province. Of 10 379 persons from five sites examined, 7 821 were infected with parasites, the overall infection rate being 75.4%. A total of 17 species of parasites were found, among which, Ascaris lumbricoides (infection rate 42.5%), hookworm (38.2%), Enterobius vermicularis (28.9%) and Trichuris trichiura (22.8%) and 5 common species of protozoa were the predominant ones. Trichinella spiralis infection (7.0%) was also noteworthy. Necator americanus is the major species of hookworm in situ , a sole situation as compared with other places of Henan.