BACKGROUND: The role of platelet function in the development of intraventricular hemorrhage is still a subject of debate. In this study, we aimed to determine whether there is an association between platelet indices in the first week of life and severity of intraventricular hemorrhage in very preterm infants. MATERIALS AND METHODS: Preterm infants born < 30 weeks of gestation in our hospital were retrospectively evaluated. Platelet parameters, including platelet counts, mean platelet volume, platelet distribution width, and platelet mass were retrieved at two different time points: the initial value on the first day of life and the value closest to the end of the first week of life. The infants were categorized according to the findings of cranial ultrasonography as; no intraventricular hemorrhage, mild or severe intraventricular hemorrhage. RESULTS: Totally, 1051 infants were evaluated. The mean gestational age and birth weight for the entire cohort were 27.9±1.6 weeks and 1058±247 g, respectively. Infants in the severe intraventricular hemorrhage group had significantly lower gestational age (p < 0.001) and birthweight (p < 0.001) compared to other two groups. Furthermore, there were significant differences in platelet count and platelet mass between the groups at two time intervals. However, logistic regression analysis revealed that only platelet count of < 100×109/L on the first postnatal day was independently associated with the severity of intraventricular hemorrhage. CONCLUSION: There is an association between platelet count of < 100×109/L on the first postnatal day and severe intraventricular hemorrhage in very preterm infants.