AbstractThe prevalence and intensity of grandparenting have continued to increase in the era of rapid aging. However, little is known about grandparents with different health statuses as primary caregivers and their implications for children's health. A nationally representative cohort of over 8990 Chinese children interviewed from 2010 to 2018 was used. Random effects logit models were constructed to assess the association of the primary caregiver type (grandparents vs. parents) and caregiver health with child health. Subsequently, additive interactions between the primary caregiver type and caregiver health were estimated to determine whether children cared for by grandparents with poor health were the most vulnerable children in terms of health. Deterioration of health status was found among children cared for mainly by grandparents, manifested as a higher likelihood of illness, depressive symptoms and unmet health care needs. However, children looked after by healthy grandparents tended to exhibit better health than their counterparts who were cared for by unhealthy parents. Grandparents as primary caregivers might not have a universally detrimental effect on child health. Thus, interventions to prompt child health could consider grandparents as caregivers, especially healthy grandparents.