This paper investigates the long-term impact of historical missionary activity on HIV in sub-Saharan Africa. On the one hand, missionaries were the first to invest in modern medicine in the region. On the other hand, Christianity influenced sexual beliefs and behaviors that affect the risk of contagion. We build a new geocoded dataset locating Protestant and Catholic missions in the early 20th century, as well as the health facilities they invested in, that we combine with individual-level Demographic and Health Survey data. With these data, we can address separately these two channels, within regions close to historical missionary settlements. First, we show that proximity to historical missionary health facilities decreases the likelihood of HIV; persistence in healthcare provision and safer sexual behaviors in the region explain this result. Second, we show that regions close to historical missionary settlements exhibit higher likelihood of HIV. This effect is driven by the Christian population in our sample. This suggests conversion to Christianity as a possible explanatory channel. Our findings are robust to alternative specifications addressing selection.