Abstract: ObjectiveTo evaluate the effects of maternal and child health(MCH)workers training on the knowledge and skill about the prevention of mother-to-child transmission of HIV in Yunnan.MethodsThe same questionnaire sur vey was conducted to 414 MCH workers in 47 counties of Yunnan before the training and to 107 MCH workers sampled from the trained subjects after one and a half year.ResultsThe awaneness rates of basic knowledge on HIV/AIDS and knowledge concerning personal protection were raised after training.The rates of correct answers to the questions such as "the window period",whether "mosquito bites transmitting HIV","the transmission route with the highest odds" and "common disinfectors can kill HIV" were raised from 68.1%,83.6%,69.1% and 61.6% to 95.3%,100%,90.7% and 94.4% respectively.The awareness rates of the voluntary consulting testing(VCT)and the prevention of mother-to-child transmission of HIV were raised significantly after training.The correct rates of answering questions such as "VCT for pregnant and lying-in women is free or not","who is the objective to be told the positive result of a HIV test" and "mother-to-child transmission of HIV can be prevented or not" were raised from 77.4%,39.7% and 78.4% to 99.1%,81.3% and 98.2% respectively.At the same time,the fear and contempt for HIV positive persons were deduced obviously.Fewer persons were afraid of contacting the HIV positives with the rate declining from 36.4% to 11.2%.ConclusionThe systemic and professional training model aiming at the combination of theory and practice improves the awareness rate of the knowledge on HIV/AIDS prevention and treatment among MCH workers,and lightens their fear of and contempt for positives.