• In a prospective study we analyzed the role of coagulopathy in the development of periventricular-intraventricular hemorrhage (PIVH) in 49 consecutively admitted preterm infants of less than 34 weeks' gestation by serial ultrasound examinations and coagulation assays. In 20 patients (41%) PIVH was detected. On the day of birth, patients with PIVH had significantly lower levels of factor V than did the patients without PIVH, but all other clotting factors gave similar results, and on the third and fifth days all results were similar, including those for factor V. Even the small subgroup of infants who subsequently developed grade IV hemorrhage did not have a more severe coagulopathy than the other infants, although they had significantly lower levels of platelets and of factor VII at birth. We conclude that coagulopathy does not play an important role in the etiology of PIVH. Standard doses of 10 mL/kg of fresh-frozen plasma, administered to increase the low levels of clotting factors, did not prevent extension of the hemorrhage.