Objective: The potential benefit of a combined adenotonsillectomy and bronchoscopy with bronchoalveolar lavage (TA-B-BAL) in preschool children with asthma has been debated in the literature. We aimed to describe the clinical course of preschool children with severe asthma undergoing this combined procedure. Study Design: This is a retrospective case-control study. Patient Selection: Preschool patients diagnosed with severe asthma who underwent TA-B-BAL treatment between 2012 and 2019 were included as cases. Controls were age and sex matched patients receiving standard asthma care. Methodology: A retrospective patient chart review was conducted. Data on demographics, clinical characteristics, medication use, virology and microbiology from bronchoalveolar lavage, and asthma control questionnaires were collected. Cases and controls were compared with t-tests and regression analysis. Results: Eighteen preschool subjects (mean age 3.19±1.13 years) in the case group were matched to eighteen control subjects receiving standard care. A Poisson mixed effects regression analysis revealed reduced risk of oral corticosteroid use (RR 0.39, 95%CI 0.18, 0.83, p=0.014), reduced emergency department visits (RR 0.36, 95%CI 0.17, 0.75, p=0.01) and reduced risk of asthma exacerbations (RR 0.58, 95%CI 0.28, 1.20, p=0.14) in cases compared to controls. Ten patients experienced clinically meaningful improvements in TRACK scores after the procedure (p<0.001). Conclusion: This pilot study provides early evidence that preschool children with severe asthma may benefit from combined adenotonsillectomy and bronchoscopy with bronchoalveolar lavage procedure. The procedure is a useful adjunct for reduction of medication use and hospital visits for preschool age patients with severe asthma.