Increasingly, health scholars acknowledge bereavement as a determinant of population health. Some research suggests that childhood health is especially affected by the deaths of family members. Although most research has focused on losing a parent or sibling in childhood, more recently, scholarship has established grandparental death as a source of poor mental health. We know less, however, about whether grandparental death affects children biologically, potentially imprinting them in a way that is consequential for their physical health and development. In this study, we offer the first analysis of the association between grandparental loss and U.S. children's telomere length-a common biomarker that reflects cumulative stress exposure. We use data from the Future of Families and Child Wellbeing Study to study grandparental death and children's telomere length at around age 9. Boys' telomere length is not associated with grandparental death; however, girls, and in particular girls who did not co-reside with their grandmother around age 5, had shorter telomere lengths following the death of their grandmother compared to girls whose grandmothers were still alive. Specifically, a non-co-resident grandmother's recent death corresponds with 11 % shorter telomeres among girls ( < 0.001), which persists net of covariates. This study demonstrates that grandparental death is a unique health risk factor for children, emphasizing the need to consider grandparental death as an underappreciated source of childhood health disparities.