INTRODUCTION: Research is needed to demonstrate the impact of child-directed advertising on household purchases of nutrient-poor children's foods to support mandatory government regulations. This study examines the relationship between total TV advertising to children versus adults and U.S. household purchases of high-sugar children's cereals. Posthoc analyses examine potential differential marginal effects of advertising on households experiencing health disparities. METHODS: Longitudinal NielsenIQ U.S. Consumer Panel Data (2009-2017) provided monthly volume (oz) of ready-to-eat cereal purchases by households with children (<
12 years) (N=76,926). Nielsen gross ratings point data measured monthly TV advertising to children (6-11 years) and adults (18-49 years) (2008-2017). A 2-part Cragg hurdle model assessed associations between child versus adult advertising for children's cereal brands (n=9) and subsequent household cereal purchases, including differences by household sociodemographic characteristics. Data were collected in 2021 and analyzed in 2023. RESULTS: Advertising to children, but not adults, was positively related to household purchases of children's cereals (p<
0.01) across all sample households. Lower price (p<
0.05) and greater household size (p<
0.01) also predicted higher purchases. Marginal effects of advertising to children were higher for Black versus non-Black households (p<
0.01), and positively related to purchases by middle/high-income (p<
0.01) but not low-income households. Advertising to adults only predicted greater children's cereal purchases by low-income households (p<
0.01). CONCLUSIONS: Advertising children's cereals directly to children may increase household purchases and children's consumption of these high-sugar products. Child-directed advertising may also disproportionately influence purchases by Black households. This study supports further restrictions on advertising of nutrient-poor foods directly to children.