Children with a secundum atrial septal defect are usually asymptomatic and are referred for elective closure after 3–4 years of age; however, in premature infants with chronic lung disease, bronchopulmonary dysplasia, or pulmonary hypertension, increased pulmonary blood flow secondary to a left-to-right atrial shunt, may exacerbate their condition. Closure of the atrial septal defect in these patients can result in significant clinical improvement. We report the cases of two premature infants with chronic lung disease, who underwent atrial septal defect closure with the Gore HELEX Septal Occluder and discuss the technical aspects of using the device in these patients and their clinical outcomes.