Postnatal closure of the ductus arteriosus is crucial in the circulatory adaptation of the newborn to extrauterine life. In recent years, many studies have been performed to improve our understanding of both the physiology of the ductus arteriosus in the fetus and newborn, and the mechanisms underlying persistent ductal patency in the preterm infant. The pharmacological treatment of patent ductus arteriosus (PDA) remains a controversial issue. This article reviews the recent literature on the pathogenesis and clinical management of PDA in the preterm infant.