Background: Childhood iron deficiency is associated with behavioral and cognitive delays. Few studies have explored the relationship between prolonged bottle-feeding and iron-deficiency anemia among toddlers. Objective: To examine the association between prolonged bottle-feeding and iron deficiency in a nationally representative sample of children ages 1 to 3 years. Design and Methods: The National Health and Nutrition Examination Survey III provides data on the feeding practices of children 1 to 3 years old and contains measures of iron status including transferrin saturation, free erythrocyte protoporphyrin, and serum ferritin. The prevalence of iron deficiency and duration of bottle-feeding were determined for black, white, and Mexican American toddlers. Bivariate and multivariate analyses were performed to examine the association between bottle-feeding duration and iron deficiency. Results: Among 2121 children ages 1 to 3 years, the prevalence of iron deficiency was 6% among whites, 8% among blacks, and 17% among Mexican Americans (P < .001). With increasing duration of bottle-feeding, the prevalence of iron deficiency among all children increased (3.8% , bottle-fed ≤ 12 months; 11.5% , bottle-fed 13- 23 months; and 12.4% , bottle-fed 24- 48 months [P < .001]). At 24 to 48 months of age, 36.8% of Mexican American children were still bottle-fed, compared with 16.9% of white and 13.8% of black children. In multivariate analyses, bottle-feeding for 24 to 48 months and Mexican ethnicity were associated with iron deficiency (odds ratio, 2.8; 95% confidence interval, 1.3- 6.0; and odds ratio, 2.9; 95% confidence interval, 1.5- 5.6, respectively). Conclusions: Children with prolonged bottle-feeding and Mexican American children are at higher risk for iron deficiency. Screening practices and nutritional counseling should be targeted at these high-risk groups. Background: Childhood iron deficiency is associated with behavioral and cognitive delays. Few studies have explored the relationship between prolonged bottle-feeding and iron-deficiency anemia among toddlers. Objective: To examine the association between prolonged bottle-feeding and iron deficiency in a nationally representative sample of children ages 1 to 3 years. Design and Methods: The National Health and Nutrition Examination Survey III provides data on the feeding practices of children 1 to 3 years old and contains measures of iron status including transferrin saturation, free erythrocyte protoporphyrin, and serum The prevalence of iron deficiency and duration of bottle-feeding were determined for black, white, and Mexican American toddlers. Bivariate and multivariate analyzes were performed to examine the association between bottle-feeding duration and iron deficiency. Results: Among 2121 children ages 1 to 3 years, the prevalence of iron deficiency was 6% among whites , 8% among blacks, and 17% among Mexican Americans (P <.001). With increasing duration of bottle-feeding, the prevalence of iron deficiency among all children increased 3.8%, bottle- fed ≤ 12 months; 11.5% bottle-fed 13- 23 months; and 12.4%, bottle-fed 24- 48 months [P <.001]). At 24 to 48 months of age, 36.8% of Mexican American children were still bottle- fed, compared with 16.9 % of white and 13.8% of black children. In multivariate analyzes, bottle-feeding for 24 to 48 months and Mexican ethnic were associated with iron deficiency (odds ratio, 2.8; 95% confidence interval, 1.3-6.0; and odds ratio, 2.9 ; 95% confidence interval, 1.5-5.6, respectively). Conclusions: Children with prolonged bottle-feeding and Mexican American children are at higher risk for iron deficiency. Screening practices and nutritional counseling should be targeted at these high-risk groups.