Objective. To determine the association between pre-bronchoscopy time of illness and post-bronchoscopy discharge time in pediatric patients with foreign body aspiration. Materials and methods. Retrospective cohort study. Medical records were studied and reviewed at the Pediatric Emergency Hospital of Lima, Peru. We reviewed 324 medical records, and selected 183 because they had the diagnosis of foreign body aspiration and complete data. Fisher's exact test and Mann Whitney U test were used for the bivariate analysis, while Poisson regression was used to calculate the Relative Risk (RR) and its 95% confidence interval (CI). Results. We included 183 patients, of whom 65.6% were men with a mean age of 2.4 years. The most frequent location of the foreign body was the right bronchial tree and most of them were made of organic material. The majority (72.7%) of patients were discharged before 24 hours. We found an association between the time of illness prior to bronchoscopy and post-bronchoscopy discharge time (RR: 2.94, 95%CI: 1.72 -- 5.01). Conclusions. The time of illness prior to bronchoscopy and the length of hospital stay after removal of the foreign body were significantly associated when adjusted for age, sex, type of foreign body and mouth sweep maneuver as a rescue measure. Our findings are relevant because they highlight the importance of early care, timely diagnosis and early management of pediatric patients. [ABSTRACT FROM AUTHOR]