Abstract
This paper shows that responses to disease risks can be "fatalistic": higher risk beliefs can lead to more risk-taking rather than less. Intuitively, this can occur because high risk beliefs raise not only the chance of contracting the disease (which raises the marginal cost of risk-taking) but also the perceived chance that you are already infected (which lowers the marginal cost). I test for fatalism by randomly providing information about the true (low) average risk of HIV transmission in Malawi. Consistent with rational fatalism, the treatment causes sexual activity to rise slightly on average but decline sharply for people with high initial risk beliefs-especially those with high baseline levels of sexual activity.