Background: In peanut and tree nut allergic children a history of anaphylaxis is associated with subsequent severe reactions. Objective: We aimed to prospectively rechallenge peanut and tree nut allergic children with a history of mild/moderate reactions to assess their allergy over time. Methods: In this cohort study peanut and tree nut allergic children with a history of mild/moderate reactions during a controlled oral challenge were invited to have a follow-up oral challenge to the same food at least 1 year later. Results: Twenty-six children participated in the study. The mean time interval between the first and second challenge for all participants was 35.5 months. Peanut or tree nut allergy resolved in 38.5% of participants. Those with persistent peanut or tree nut allergy showed a decrease in their reaction threshold and/or increased severity in 81% of cases. There were no demographic features or skin test results that were predictive of changes in severity over time. Conclusion: Peanut and tree nut allergic children with a history of mild/moderate reactions who remained allergic demonstrated a high rate of more severe reactions and/or reduced thresholds upon rechallenge over a year later, however, the rate of resolution of allergy in this group may be higher than previously reported.