The crucial role of platelets in the permanent closure of the ductus arteriosus has recently been elucidated in an animal model; however, clinical studies investigating the impact of platelet count on ductal patency have conflicting results. Our aim is to compare platelet count, indices and serum platelet-derived growth factor levels in preterms with and without ductal patency. Preterms with a gestational age of 27-30 weeks followed up during a twelve-month period in the neonatal intensive care unit of Adnan Menderes University Hospital were enrolled. Infants underwent echocardiographic evaluation starting on the second day and subsequently assessed every other day until ductal closure was achieved, or upon clinical signs of reopening. Platelet-derived growth factor was measured on the second and fifth days of life. Eleven very low birth weight infants who subsequently required medical treatment for patent ductus arteriosus were compared with twenty-three infants with closed ductus. Although platelet count and indices were similar, median serum plateletderived growth factor levels on day 5 were significantly lower among babies who subsequently required medical treatment for ductal patency (874.6 vs 1099.6 pg/ml). The current study points out a possible association between serum platelet-derived growth factor levels and ductal closure. Our results suggest that platelet-derived growth factor may play a role in ductal closure independent from platelet count and might be used as an adjunct surrogate for prediction of future need for treatment for hemodynamically significant patent ductus arteriosus in preterm infants.