Between 1975 and 1979, upwards of two million men, women, and children perished in the Cambodian genocide. Decades after the ending of mass violence, Cambodia struggles both with reconciliation and remembrance. These struggles figure prominently in the representation of mass violence at state-sanctioned sites of memorialization, specifically the Tuol Sleng Genocide Museum. In this paper, I draw inspiration from Derrida’s conceptualization of hauntology to provide a critical reading of the Tuol Sleng Genocide Museum. A multivalent concept, haunting directs attention to the traces or remains – whether material or discursive – of violence that remain present in their absence. Consequently, the museum – a popular destination on the dark tourism circuit – reproduces a particular knowledge of Cambodia’s genocide, that is, a state-sanctioned interpretation of Khmer Rouge violence. At the same time, the historical and geopolitical context of the genocide, notably the extension of the United States-led war in Vietnam, haunts the museum’s display of violence by its conspicuous absence. In doing so, I provide a critique of epistemological practices at the Tuol Sleng Genocide Museum and highlight the tension of absent-presences that haunt the display of genocidal violence in Cambodia