This paper focuses on the question of why fairness matters to people. Extending on terror and uncertainty management theories and the literature on the self, it is proposed here that fairness can be a means of self-defense. Thinking of a situation that is threatening to the self therefore should make fairness a more important issue to people. The findings of two experiments support this line of reasoning: Asking participants to think about things that are threatening to themselves led to stronger reactions to manipulations of both procedural and distributive fairness. In the discussion it is argued that these findings suggest that fairness especially matters to people when they are trying to deal with threats to their selves.