The developing world has notoriously low female-to-male sex ratios, a phenomenon that has been described as ‘missing women’. It is argued that this is driven by parental preferences for sons, sex-selective abortion, and different levels of care during infancy. This column shows that these higher rates of female mortality continue into adulthood. It argues that being unmarried, especially through widowhood, can have substantial effects on relative rates of female mortality in the developing world.