The automatic and affective nature of moral judgments leads to the expectation that these judgments are biased by an observer’s own interests. Although the idea of self-interest bias is old, it has never been directly tested with respect to the moral judgments of other individuals’ behaviors. The participants of three experiments observed other individuals’ counternormative behavior (breaking a rule or cheating for gain), which was judged as immoral. However, this judgment became much more lenient when the observers gained from the observed behavior. All three studies showed that the influence of self-interest on moral judgments was completely mediated by the observer’s increased liking for the perpetrator of the immoral acts but not by changes in mood. When the participants were induced to dislike the perpetrator (in a moderation-of-process design), the self-interest bias disappeared. Implications for the intuitionist approach to moral judgment are discussed.