To assess the effect of treating pulmonary hypertension (PH) in infants less than 1 year of age with systemic glucocorticoids while using echocardiographic and diagnostic biomarkers as measures of efficacy. A retrospective chart review was performed on 17 hospitalized infants less than one year of age at St. Louis Children's Hospital who received a five- to seven-day course of systemic glucocorticoid treatment followed by a three-week taper with no significant intracardiac shunts from January 1, 2017, to December 31, 2021. Quantitative echocardiographic indices for PH, N-terminal pro b-type natriuretic peptide (NT-proBNP) and/or b-type natriuretic peptide (BNP) levels were collected pre-glucocorticoid treatment, after the glucocorticoid burst, and following the 21-day taper. Mean (+/- SD) gestational age was 32.1 (+/-5.8) weeks, 5 infants were (29%) concomitantly treated with sildenafil, and 8 were male. Twelve were classified as World Health Organization (WHO) group 3 PH (71%), and 5 WHO group 1 PH. There were significant improvements 30 days post-glucocorticoid initiation in BNP levels (p=0.008), partial pressure of carbon dioxide (p=0.03), eccentricity index (p=0.005), RV ejection time (p=0.04), pulmonary artery acceleration time (PAAT) (p=0.002), and PAAT to right ventricular ejection time ratio (PAAT/RVET) (p=0.02). Tricuspid regurgitation velocity was not able to be assessed. There were no mortalities during the study timeline. In our retrospective study, systemic glucocorticoid therapy was well tolerated and appeared to be associated with significant improvement in cardio-pulmonary function in infants with PH. Further prospective study in a larger sample is warranted.