Aspects of the long-term demographic impact of genocide during the period of the Khmer Rouge (1975–79) in Cambodia are analyzed. Mortality data for siblings from the Cambodia Demographic and Health Survey in 2000 demonstrate that excess mortality was extremely high and heavily concentrated during 1974–80. The study also shows that mortality was highly selective during that period. Adult males were the most likely to die, indicating that violent death played a major role. Individuals with an urban or educated background were more likely to die. Mortality by religious background is also assessed. Infant and early childhood mortality was very high during the period and was as prevalent in urban areas and among children born to educated mothers as in rural areas and among the less educated.