In order to understand the status of HIV infection in the population under high risk, we conducted an epidemiological investigation among 396 persons from 1992 to 1995. The research sample included 55 female prostitutes, 159 labourers who had finished labour services abroad upon returning, 88 professional blood donors, 88 STD patients, 3 spouses and 3 children of the HIV infected people. Six cases of HIV positive were identified in four years. Among these, two were blood donors with one male and one female, the other four cases were all male labourers returned from abroad.