In infants with respiratory distress syndrome (RDS) hypoxemia inhibits closure of the patent ductus arteriosus (PDA), resulting in increased pulmonary blood flow with subsequent increased hypoxemia. In an attempt to interrupt this cycle 42 consecutive premature infants with RDS and PDA, weighing between 550 and 2,000 gm (average, 1,383 gm) and with an average gestational age of 31 weeks, were arbitrarily treated either medically (13 patients) or by interruption of the PDA (20 patients). Eleven patients who were initially treated medically could not be weaned from the respirator and later underwent operation. There were no operative or anesthetic deaths; late survival was 65% (20 patients). The last 31 patients were randomly divided into operative and nonoperative groups. Preliminary results revealed no significant differences in late survival between the two groups. Since the operative risk is minimal, further investigative efforts are indicated to settle this issue.