The use of heuristic biases and the false consensus effect can lead individuals to misperceive risk of HIV infection. The current paper presents the results of two studies which sought to examine whether individuals, (a) weigh risk relevant information accurately in their assessments of HIV risk, and (b) are susceptible to the false consensus effect in their assessments of actual intimate partner risk behaviors. The results of the first study support the hypothesis that individuals do not use objective risk information based on probability statistics in their assessments of HIV risk. In addition, the results of the second study find that female partners exhibit the false consensus effect regarding sexual risk behaviors, whereas male partners did not. Discussion centers on the role of perceptual biases in HIV risk behaviors among individuals in intimate relationships.