Abstract: BACKGROUND: There remains controversy regarding the outcomes resulting from treatment versus conservative management of patent ductus arteriosus (PDA) among preterm infants. The effects of extreme prematurity, hemodynamic status of the PDA, and age at treatment remain poorly defined. STUDY DESIGN: This retrospective case-control study including infants < 1250 gm who were categorized into 3 groups: Group 1: without PDA, Group 2: with untreated PDA, and Group 3: treated PDA. Diagnosis and treatment of PDA extracted from the medical records. Demographics, clinical characteristics, and outcomes compared using chi-square and analysis of variance. Logistic regression used to estimate adjusted odds ratios. RESULTS: The study included 734 infants, with 141(19%) in Group 1, 329 (45%) in 2, and 264 (36%) in 3. Group 3 had higher incidence of bronchopulmonary dysplasia (BPD) (aOR, 2.9; 95%CI 1.7–4.8). Infant treated for hemodynamically significant PDA (HSPDA) had higher incidence of BPD (aOR, 1.9; 95%CI 1.0–3.8) and retinopathy of prematurity (ROP) (aOR, 3.4; 95%CI 1.6–6.9). There were no differences in outcome associated with treatment among≤26 weeks gestation and the age when treated. CONCLUSION: Infants with PDA who were treated had higher incidence of BPD. Among those who were treated, those with HSPDA had a higher incidence of BPD and ROP.