© 2015 Palmer et al. Background: In recent years the role of vitamin D status in early life on the development of allergic disease has generated much interest. The aim of this study was to determine whether cord blood vitamin D concentrations were associated with risk of early childhood allergic disease. Methods: Measurements of cord blood 25-hydroxyvitamin D [25(OH)D] concentrations were available in 270 mother-child pairs who were participating in the allergy follow-up (n∈=∈706) of the Docosahexaenoic Acid to Optimise Mother Infant Outcome randomised controlled trial. All of the children had a hereditary risk of allergic disease. The diagnosis of allergic disease was made during medical assessments at 1 and 3 years of age. Results: The mean (standard deviation) standardised cord blood 25(OH)D concentration was 57.0 (24.1) nmol/L. The cumulative incidence of eczema to 3 years of age, n∈=∈101/250 (40 %) was associated with standardised cord blood 25(OH)D concentration, with a 10 nmol/L rise in 25(OH)D concentration reducing the risk of eczema by 8 % (relative risk 0.92, 95 % confidence interval 0.86-0.97; P∈=∈0.005). This association was stronger at 1 year of age, when a 10 nmol/L rise in standardised cord blood 25(OH)D concentration reduced the risk of eczema by 12 % (relative risk 0.88, 95 % confidence interval 0.81-0.96; P∈=∈0.002). No associations between cord blood 25(OH)D concentrations and development of allergic sensitisation, allergic rhinitis or asthma in early childhood were found. Conclusion: In children with a family history of allergic disease, a higher cord blood 25(OH)D concentration appears to be associated with reduced risk of eczema in early childhood. Trial registration: Australian New Zealand Clinical Trials Registry ACTRN12610000735055 (DOMInO trial: ACTRN12605000569606).