['To determine whether eosinophil-derived neurotoxin (EDN) is a predictive marker of recurrent wheezing episodes in post-respiratory syncytial virus (RSV) bronchiolitis.', 'EDN levels and recurrent wheezing episodes were serially measured in 200 infants hospitalized with RSV bronchiolitis.', 'Serum EDN levels at 3 months correlated significantly with total wheezing episodes at 12 months in the RSV-PLC (n \u2009= 71; r = 0.720, p < 0.0001) and RSV-MONT groups (n = 79; r = 0.531, p < 0.001). Positive predictive value of 3-mo EDN level for total wheezing episodes was 57%; negative predictive value, 76%; sensitivity, 72%; specificity, 62%.'] Are eosinophil-derived neurotoxin levels at 3 months post-respiratory syncytial virus bronchiolitis a predictive biomarker of recurrent wheezing?