We estimate and decompose income-related inequality in child health in the USA and analyze its dynamics using the recently introduced health mobility index. Data come from the 1997, 2002, and 2007 waves of the Child Development Supplement of the Panel Study of Income Dynamics. The findings show that income-related child health inequality remains stable as children grow up and enter adolescence. The main factor underlying income-related child health inequality is income itself, although other factors, such as maternal education, also play a role. Decomposition of income-related health mobility indicates that health changes over time are more favorable to children with lower initial family incomes versus children with higher initial family incomes. However, offsetting this effect, our findings also suggest that changes in income ranking over time are positively related to children's subsequent health status. Copyright © 2012 John Wiley & Sons, Ltd.