Background: Although recent studies suggest that eczema in early childhood is important in the development of food allergy, the importance of the timing of eczema onset has not been fully clarified. Objective: This study aim to identify an association between the timing of eczema onset and development of food allergy in a prospective birth cohort study. Methods: Data were obtained from the Tokyo Children's Health, Illness and Development (T-CHILD) study, which is a hospital-based birth cohort study currently in progress in Japan. A total of 1550 children were born to the recruited women. Outcome data for children were collected from questionnaires completed at 6 months, 1 and 3 years of age. Association between the timing of eczema onset and development of food allergy was estimated by logistic regression analyses. All analysis were performed using SPSS software with a two-sided 5% significance level. Results: Eczema in the first year of life was a significant risk factor in multivariate analysis (aOR 3.90, 95% CI 2.34-6.52, p < 0.001). In each age (by month) stratum, infants with onset of eczema within the first 1-2 months after birth had the highest risk of food allergy at 3 years of age (aOR 6.61, 95% CI 3.27-13.34, p < 0.001). Conclusion: Infants with early eczema onset (especially within the first 1-4 months after birth) were found to have an increased risk of developing food allergy at 3 years of age. Our findings may contribute to a better understanding of the timing of eczema onset as a potentially modifiable risk factor and to defining those who may need to be on guard for food allergy. (C) 2016 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.