After 4 years implementing interventions activites under the Project HIV/AIDS financed by the WB, a survey on 788 ethnic Thai in 4 communes/towns of Quan Hoa district, Thanh Hoa province has shown remarkably effective: The percentage of people who correctly and fully understand the three routes of transmission of HIV/AIDS has increased from 47.9 percent to 56.6 percent, p 0.001 and the effect rate reached 18.2 percent. The rate of subjects with true understanding about prevention of HIV transmission from mother to child i increased more than before the intervention, the difference is statistically significant, effect rate reached 3.8 percent - 77.1 percent. Objects have more positive attitudes about HIV/AIDS, the difference is statistically significant with p 0.001, effect rate reached 5.9 percent 82.7 percent. The rate of subjects using condoms during last sex and the rate of this object using condoms during sexual encounters most of the past year are up more than before the interventio effect rate reached 226.3 percent and 79.2 percent. The rate of subjects had HIV/AIDS test in the past year increased from 3.3 percent to 16.2 percent, p0.001, effect rate reached 390.9 percent.