We hypothesized that early life exposure to nucleotides and nucleosides lowers the risk of recurrent wheeze, atopic dermatitis, and allergic sensitization among n = 429 children. Concentrations in breast milk were established by high-performance liquid chromatography; concentrations in formula milks were obtained from manufacturers. Questionnaires and home visits were used to assess outcomes. Adjusted odds ratios in the highest tertile compared with those in the lowest tertile of exposure ranged from 1.11 to 1.99 in predominantly formula-fed children, and from 0.40 to 0.53 in predominantly breast-fed children, but were not significant. Thus, we found no evidence for association between nucleotide and nucleoside exposure and the development of atopic outcomes in children up to 2 years.