Importance: Treatment options for a symptomatic pneumothorax in newborns include needle aspiration (NA) and chest drain (CD) insertion. There is little consensus as to the preferred treatment, reflecting a lack of evidence from clinical trials. Objective: To investigate whether treating pneumothoraces diagnosed on chest radiography (CR) in newborns receiving respiratory support with NA results in fewer infants having CDs inserted within 6 hours of diagnosis. Design, Setting, and Participants: This randomized clinical trial was conducted from October 7, 2013, to December 21, 2016. The setting was 5 tertiary European neonatal intensive care units. Infants receiving respiratory support (endotracheal ventilation, continuous positive airway pressure, or supplemental oxygen >40%) who had a pneumothorax on CR that clinicians deemed needed treatment were eligible for inclusion. Interventions: Infants were randomly assigned (1:1) to drainage using NA or CD insertion, stratified by center and gestation at birth (<32 vs ≥32 weeks). Caregivers were not masked to group assignment. For NA, a needle was inserted between the ribs to aspirate air and was removed once air was no longer aspirated. A CD was inserted if clinicians deemed that the response was inadequate. For CD insertion, a drain was inserted between the ribs and was left in situ. Main Outcomes and Measures: The primary outcome was whether a CD was inserted on the side of the pneumothorax within 6 hours of diagnosis. Results: A total of 76 infants were randomly assigned, and 6 (4 assigned to NA and 2 to CD) were excluded because they met exclusion criteria at enrollment. Of the 70 remaining infants, 33 (16 male [48%]) were assigned to NA and 37 (22 male [59%]) to CD insertion. Their median (interquartile range [IQR]) gestational age was 31 (27-38) vs 31 (27-35) weeks, and their median (IQR) birth weight was 1385 (1110-3365) vs 1690 (1060-2025) g, respectively. Fewer infants assigned to NA had a CD inserted within 6 hours (55% [18 of 33] vs 100% [37 of 37]; relative risk, 0.55; 95% CI, 0.40-0.75) and during hospitalization (70% [23 of 33] vs 100% [37 of 37]; relative risk, 0.70, 95% CI, 0.56-0.87). Conclusions and Relevance: Needle aspiration reduced the rate of CD insertion in symptomatic newborns with pneumothorax on CR. It should be used as the initial method of draining radiologically confirmed pneumothorax in symptomatic infants. Trial Registration: isrctn.org Identifier: ISRCTN65161530.