Objective: To validate the bronchiolitis score of Sant Joan de Déu (BROSJOD) and to examine the previously defined scoring cutoff. Patients and Methods: Prospective, observational study. BROSJOD scoring was done by two independent physicians (at admission, 24 and 48 hr). Internal consistency of the score was assessed using Cronbach's α. To determine inter-rater reliability, the concordance correlation coefficient estimated as an intraclass correlation coefficient (CCC) and limits of agreement estimated as the 90% total deviation index (TDI) were estimated. An expert opinion was used to classify patients according to clinical severity. A validity analysis was conducted comparing the 3-level classification score to that expert opinion. Volume under the surface (VUS), predictive values, and probability of correct classification (PCC) were measured to assess discriminant validity. Results: About 112 patients were recruited, 62 of them (55.4%) males. Median age: 52.5 days (IQR: 32.75–115.25). The admission Cronbach's α was 0.77 (CI95%: 0.71; 0.82) and at 24 hr it was 0.65 (CI95%: 0.48; 0.7). The inter-rater reliability analysis was: CCC at admission 0.96 (95%CI 0.94–0.97), at 24 h 0.77 (95%CI 0.65–0.86), and at 48 hr 0.94 (95%CI 0.94–0.97); TDI 90%: 1.6, 2.9, and 1.57, respectively. The discriminant validity at admission: VUS of 0.8 (95%CI 0.70–0.90), at 24 h 0.92 (95%CI 0.85–0.99), and at 48 hr 0.93 (95%CI 0.87–0.99). The predictive values and PCC values were within 38–100% depending on the level of clinical severity. Conclusion: There is a high inter-rater reliability, showing the BROSJOD score to be reliable and valid, even when different observers apply it. Pediatr Pulmonol. 2017;52:533–539.