Abstract: Military sexual assault (MSA) survivors are particularly likely to engage in sexual risk-taking, or sexual behaviors that may result in sexually transmitted infections or unintended pregnancy. Theory suggests that posttraumatic cognitions, including negative thoughts about the self, negative thoughts about the world, and self-blame, may be a salient factor related to sexual risk-taking in this population. Further, sex differences have been observed in both posttraumatic cognitions and sexual risk-taking. In this secondary analysis of web-based survey data collected from U.S. service members and veterans (N = 400, 50.0% male), we hypothesized that posttraumatic cognitions would be positively associated with sexual risk-taking and that sex would moderate this effect. The moderation model significantly predicted sexual risk-taking, R2 = .19, F(6, 391) = 15.60, p < .001, and the effect of posttraumatic cognitions on sexual risk-taking significantly differed by sex, B = 0.13 (SE = .05), p = .009, such that it was stronger for male survivors, B = 0.22 (SE = .03), p < .001, than female survivors, B = 0.09 (SE = .04), p = .019. Exploratory post hoc moderation analyses revealed a similar pattern for both negative thoughts about the self and self-blame, whereas negative thoughts about the world did not differ by sex. The results point to the potential utility of cognitive-based therapies in reducing sexual risk-taking after MSA, particularly among male survivors, and highlight the importance of investigating psychological and interpersonal outcomes in this population. This study provides a vital contribution to the small literature base regarding male MSA survivors.