In remarks scattered across his corpus of writings, Nietzsche offers a fascinating analysis of the theme of purity. In this article I systematize these fragments into a genealogy and draw out conclusions relevant to philosophy and cultural criticism. Nietzsche argues that the Christian use of purity, as both an ideal and a means of achieving self-martyrdom of the will, has been retained in modern Western culture. He is generally quite skeptical of purity, considering it to be tightly associated with dominating and mediocratic social institutions. However, he also sees potential for purity to help bring about an escape from these systems of social control.