We investigated how people respond to moral threats and the consequences this has for one's moral self-concept. In two experiments, participants first tasted a sausage and were then confronted with a bogus participant who had refused to taste the sausage because of moral or non-moral reasons. People disliked the moral refuser more than the non-moral refuser. The self-threatening effect of having one's morals questioned was also reflected in specific patterns of cardiovascular responses and negatively affected participants' self-evaluations. We further show that the negative effects of a moral threat can be prevented by a simple intervention of physical cleansing: Participants who had cleansed their hands before being confronted with a moral refuser did not show the negative effects on self- and refuser evaluations. Importantly, the protective effects of physical cleansing were most pronounced for people with a strong moral identity. Taken together, these results underline the importance of one's self-concept when confronted with a moral refuser, and introduce an effective intervention to prevent these negative consequences.