This paper reported an epidemiological investigation on human and animal Eperythrozoons infection in five districts from three provinces in China. The results showed that Eperythrozoon infection appeaned in human as well as in swines, sheep and cats. Due to geographical variations, the infectious rates showed significanty difference both in human and in animals. The infection rate in human was not associated with sex, age or occupation. Some questions related to the epidemiology of Eperythrozoonosis were discussed in this article.