This study investigated the effects of obesity myths on blame attribution and the perceived credibility of both an alleged sexual assault victim and her perpetrator. Participants were randomly assigned to one of three sexual assault scenarios (in which either the victim or the perpetrator was described as obese and one in which both were described as obese) and responded to questions measuring the blame attribution and perceived the credibility of both individuals. A main effect of scenario was found on the perpetrator’s credibility, indicating that participants rated the obese perpetrator as more credible when the victim was obese in comparison with when the victim was nonobese. However, no main effect of scenario was found on the victim’s credibility and blame attribution, denoting that the victim’s or perpetrator’s weight did not influence participants’ perceptions of the victim’s credibility or blame attribution. The belief in obesity myths was the most significant predictor of victim blaming. However, differing patterns of the effects of obesity myths were found on the victim’s credibility and the perpetrator’s credibility. The belief in obesity myths was a significant predictor only when the victim was obese, whereas it was not a significant predictor in the scenarios where both the victim and the perpetrator were obese or the perpetrator was obese and the victim was nonobese. As for the perpetrator’s credibility, the belief of obesity myths was not a significant predictor. Instead, the scenario was a significant predictor. Implications of obesity-myth endorsement in relation to sexual assault are discussed.