Previous studies suggest that there is a systemic activation of clotting and fibrinolysis in preterm infants with advanced respiratory distress syndrome (RDS). However, there are no data on the hemostatic status in the early stages of the disease; therefore, we studied some of the hemostatic parameters in these patients and made several studies at different times in preterm infants who did or did not develop RDS, using similar protocols. We found normal plasma fibrinogen, protein C, protein S, C4b-binding protein, thrombomodulin, antithrombin III, thrombin-antithrombin III complex, prothrombin fragment 1.2, plasminogen, tissue plasminogen activator, alpha-1 antitrypsin, alpha-2-macroglobulin and protein Z. However, lower D-dimer and higher plasminogen activator inhibitor and von Willebrand factor antigen levels were found within six hours of life in infants who later developed RDS compared to the control group. These findings suggest that disseminated intravascular coagulation is not prominent in the early stages of RDS. Moreover, reduced D-dimer and increased plasminogen activator inhibitor and von Willebrand factor antigen levels are probably related to the abnormalities in the fibrinolytic mechanism due to lung damage in RDS, but further studies are needed to show their pathogenic significance in RDS.