During 1975, 38 of 44 infants with a birth weight of less than or equal to 1,500 gm who developed pulmonary edema and congestive heart failure due to a patent ductus arteriosus were managed medically until the ductus closed spontaneously days or weeks later. Overall survival was 71%, and there were no deaths among 11 infants weighing more than 1,250 gm. Pulmonary complications were prevalent and were attributed to the extensive use of mechanical ventilation required to control pulmonary edema. The results of this study document the results to be expected when small preterm infants with a symptomatic patent ductus arteriosus are managed without surgical or pharmacologic intervention and provide a basis for the rational design of clinical trials evaluating other management approaches.