not-yet-known not-yet-known not-yet-known unknown Objective: To investigate use of asthma controller medications and their effect on lung function in pediatric patients with SCD. Methods: Retrospective study in pediatric patients of African American ethnicity with SCD treated at PCH between 2014-2021. Associations of asthma controller medications with changes in lung symptoms (cough, wheeze, chest pain, shortness of breath with exercise, sleep disturbance), Acute Chest Syndrome (ACS), and percent predicted spirometry (FEV 1, FVC, FEV 1/FVC, FEF 25%-75%)) were examined (Fisher exact, Wilcoxon rank sum) separately in SCD patients with and without asthma. Results: Of the total 98 SCD patients, 28 (29%) had an asthma diagnosis. Asthma controller medications were prescribed to 20 (71% of 28) with asthma and 37 (53% of 70) without asthma. Patients with vs without asthma were more likely to receive combined medications (55% vs 8.1%), but less ICS alone (35% vs 48 %) or LTRA alone (10% vs 43%) (p<0.0003). Medication use vs non-use improved cough (38% vs 9%, P=0.006) and shortness of breath with exercise (32% vs 12%, P=0.03) in SCD patients without asthma, but these were non-significant in asthmatics. Medications also improved the mean percent change in both non-asthmatics FEV 1 (10.2 vs -3.2; P<0.0001), FVC (8.8 vs -0.7; P=0.002), and FEF 25%-75%, (17.6 vs -9.7; P=0.0005), and asthmatics FEV 1 (16.4 vs -5.2; P=0.001), FVC (13.7 vs -3.8; P=0.0009), and FEF 25%-75%, (26.1 vs -5.0; P=0.02). Conclusion: These findings, demonstrating improved lung function with asthma controller medications in pediatric patients with SCD, irrespective of an asthma diagnosis, holds great promise for this undertreated population.