Abstract: This study investigates the effect of China’s Compulsory Schooling Law (CSL) on the contraction of AIDS and related mortality. We find that the CSL significantly improves knowledge of the transmission routes of HIV. However, the evidence on its effects on sexual transmission is mixed. On the one hand, the CSL reduces incidence of teen pregnancy. On the other hand, it decreases women’s desired fertility and leads them to seek female contraceptive methods. This, in turn, reduces the overall use of condoms, which are proved to be the only effective means to prevent sexually transmitted infections. During the 1990s, HIV was transmitted mainly through reused needles during unsanitary blood donations in China. By contrast to the ambiguous evidence on sex transmission, we find consistent evidence that the CSL results in a reduction of AIDS contraction through blood transmission. First, we find that longer exposure to the CSL decreases the incidence of blood samples with Hepatitis B and C, which are the most prevalent blood-transmitted diseases, suggesting a lower risk of blood infection. Second, we find that the CSL causes a significant and sharp reduction in AIDS contraction and mortality in the four provinces most involved in the “plasma economy”, where people have donated their blood in exchange for money. Supplementary evidence shows that the CSL increases employment and income, which is likely to raise the opportunity cost for unsanitary blood donation. This study sheds light on the variations of the AIDS epidemic across different countries and is the first to investigate the effect of education on HIV through blood transmission.