The ductus arteriosus frequently fails to close in premature neonates. Considerable difference in opinion exists around what signifies a hemodynamically significant patent ductus arteriosus (PDA) and how reliable clinical signs are in determining the degree of the left-to-right shunting. Although reliance on clinical signs alone could delay the diagnosis of a PDA, there is insufficient evidence to suggest that early treatment improves outcome. Echocardiography is often used as the gold standard for diagnosing a PDA. A combination of echocardiographic measurements may assist in the early diagnosis of a PDA with a hemodynamically significant degree of left-to-right shunting, especially in extremely premature babies, where closure can be significantly delayed. Decision to treat PDA should be based on a combination of clinical signs and echocardiographic parameters. Monitoring B-type natriuretic peptide may be useful in the diagnosing neonates with symptomatic PDA.