People are known to be susceptible to psychological essentialism when reasoning about organ transplantation, believing that the mental characteristics of the donor will transfer to the recipient. Because psychological essentialism is exacerbated in negative social contexts (i.e., moral contagion bias), the effect may be especially apparent when people consider the impact of receiving organs from donors who died by stigmatized causes, such as suicide and homicide. In a forced-choice paradigm, participants overwhelmingly ranked a suicide victim as their least preferred donor, with accident victims being the most preferred donors and homicide victims the most common second choice. In a follow-up study, we investigated the psychological mechanisms underlying this unease about suicide donors. Compared to those who imagined receiving a heart from homicide or accident victims, participants who imagined a suicide donor expressed greater unease about the source of their transplant. The effect could not be explained by participants’ rumination about the source of the transplant, or by the explicitly perceived stigma of suicide, but did depend on their essentialist beliefs. Those who believed that negative or neutral (but not positive) traits of the donor could transfer to them were more hesitant about receiving a heart from a suicide relative to other donors. These data suggest that the bias against suicide organ donors is moderated by socially relevant essentialist beliefs.