Intraventricular hemorrhage (IVH) in premature infants may be related to the immaturity of the vascular bed in the germinal matrix. We measured six hemostatic parameters whose alterations may represent an additional risk factor for IVH in preterm infants. On postnatal day 1 there were differences between plasminogen activator inhibitor-1 (PAI-1) activity and antigen, of both full-term and preterm infants with and without IVH (P < 0.05). Preterms with IVH were different to both full-terms and preterms without IVH. No difference was observed in plasma concentrations of fibrinogen, plasminogen and von Willebrand factor. Plasma concentrations of antithrombin III were significantly higher in full-term infants than in preterm infants. The difference between the platelet counts of preterm infants with and without IVH was not significant (P > 0.05). Elevation of crosslinked fibrin degradation products (XDP), determined by the SimpliRED D-dimer test, correlated in four out of five premature infants with the diagnosis of IVH by ultrasonography. No elevation of D-dimer XDP was observed in premature infants without IVH (11/12) and full-term infants (6/6). In conclusion, a hypercoagulable state, indicated by a rise in D-dimer XDP, may be initiated by some types of trauma to fragile blood vessels of the preterm infants who develop IVH. This hypercoagulability is further exacerbated by the increased release of PAI-1 leading to suppressed fibrinolysis.