Background: Safe and cost-effective biological surrogate markers to evaluate the severity and threshold dose of peanut allergy (PA) reactions during an oral food challenge (OFC) are lacking. Objective: To evaluate biological markers associated with the severity and threshold dose of allergic reaction during OFC in a population of children with PA. Methods: Demographic and biologic parameters of children with peanut OFC and BAT results were collected. Patients were stratified into two severity groups (mild-to-moderate and severe) and two cumulative threshold dose groups: low (LCTG) ≤100mg crushed peanut; and high (HCTG) >100mg. Results: Among the 68 children included there was a 96% concordance between the OFC and BAT result for the diagnosis of PA. Of the 56 children with a positive OFC and BAT to peanut (median age: 8.8 years), severity of allergic reaction and cumulative threshold dose were not correlated (p=0.24). Higher Ara h 2-specific IgE and FcεRI-positive control values were both associated with severe reactions to peanut. Combining these two markers led to a 92% sensitivity [84%-97%] and 82% specificity [71%-89%] for severe reactions in all subjects. For children in the LCTG, a 4-variable composite marker including age, normalized basophil sensitivity (EC50), and FcεRI- and fMLP-positive control values, resulted in 97% sensitivity [89%-99%] and 61% specificity [49%-71%] CONCLUSION: Distinct composite markers including BAT allergen-specific and non-allergen-specific parameters appear to be associated with severity and cumulative threshold dose in children with PA.