Disgust originated as an evolutionary adaptation for avoiding disease, but it has since infiltrated morality. Many philosophers are skeptical of moral disgust. Skeptics argue that disgust is unreliable and harmful, and that we should eliminate or minimize feelings of disgust in moral thought. However, these arguments are unsuccessful. They do not show that disgust is more problematic than other emotions implicated in morality. Moreover, empirical research suggests that disgust supports important norms and values. Disgust is frequently elicited by “reciprocity violations,” i.e., acts of cheating, dishonesty, and exploitation. The emotion is a fitting response because it accurately reflects the ability of these moral wrongs to pollute and to circulate. Repurposing its original functions, moral disgust motivates social exclusion, tracks the spread of immorality, and acts as a signaling system to coordinate sanctioning. Instead of expunging ourselves of moral disgust, then, we should seek to understand its virtues and its vices.