OBJECTIVE: We examined whether the risk of food-allergen sensitization varied according to self-identified race or genetic ancestry. METHODS: We studied 1104 children (mean age: 2.7 years) from an urban multiethnic birth cohort. Food sensitization was defined as specific immunoglobulin E (sIgE) levels of >/= 0.35 kilo-units of allergen (kUA)/L for any of 8 common food allergens. Multivariate logistic regression analyses were used to evaluate the associations of self-identified race and genetic ancestry with food sensitization. Analyses also examined associations with numbers of food sensitizations (0, 1 or 2, and >/= 3 foods) and with logarithmically transformed allergen sIgE levels. RESULTS: In this predominantly minority cohort (60.9% black and 22.5% Hispanic), 35.5% of subjects exhibited food sensitizations. In multivariate models, both self-reported black race (odds ratio [OR]: 2.34 [95% confidence interval [CI]: 1.24-4.44]) and African ancestry (in 10% increments; OR: 1.07 [95% CI: 1.02-1.14]) were associated with food sensitization. Self-reported black race (OR: 3.76 [95% CI: 1.09-12.97]) and African ancestry (OR: 1.19 [95% CI: 1.07-1.32]) were associated with a high number (>/= 3) of food sensitizations. African ancestry was associated with increased odds of peanut sIgE levels of >/= 5 kUA/L (OR: 1.25 [95% CI: 1.01-1.52]). Similar ancestry associations were seen for egg sIgE levels of >/= 2 kUA/L (OR: 1.13 [95% CI: 1.01-1.27]) and milk sIgE levels of >/= 5 kUA/L (OR: 1.24 [95% CI: 0.94-1.63]), although findings were not significant for milk. CONCLUSIONS: Black children were more likely to be sensitized to food allergens and were sensitized to more foods. African ancestry was associated with peanut sensitization.