Atopic dermatitis is common in infancy. The role of food allergy in atopic dermatitis of infancy is unclear. We examined the relationship between atopic dermatitis and immunoglobulin E (IgE)-mediated food allergy in infancy. A birth cohort of 620 infants with a family history of eczema, asthma, hayfever or immediate food allergy in a parent or sibling: 487 children had complete data including skin prick tests (SPTs) to evaluate IgE-mediated food allergy to cow milk, egg and peanut. Participants were grouped as no atopic dermatitis (Gp 0) or in quartiles of increasing severity of atopic dermatitis (Gps 1-4) quantified by days of topical steroid use as reported monthly. Adverse reactions to foods were recorded. The cumulative prevalence of atopic dermatitis was 28.9% to 12 months (10.3% of the cohort of moderate severity). As atopic dermatitis severity increased so did the prevalence of IgE-mediated food allergy (Gp 0, 40/346 vs. Gp 1, 6/36 vs. Gp 2, 8/35 vs. Gp 3, 12/35 vs. Gp 4, 24/35; chi(2) = 76; p < 10(-6)), and the frequency of reported adverse food allergy reactions (Gp 0, 43/346 vs. Gp 1, 4/36 vs. Gp 2, 8/35, vs. Gp 3, 5/35, vs. Gp 4, 13/35; chi(2) = 17; p = 0.002). The relative risk of an infant with atopic dermatitis having IgE-mediated food allergy is 5.9 for the most severely affected group. Atopic dermatitis is common in infancy. There is a strong association between IgE-mediated food allergy and atopic dermatitis in this age group.