The previously reported activated intravascular coagulation system in the acute phase of respiratory distress syndrome (RDS) has not been evaluated in the long term. We assessed the activities of coagulation system of a cohort of premature infants with RDS in comparison with healthy premature infants (HPIs), healthy mature infants (HMIs), and pediatric laboratory controls over a 6-month period. Cord and venous blood samples were taken at birth, at the first month and sixth month. Protein C (PC), free protein S (f-PS), and antithrombin (AT) activities, thrombin-antithrombin (TAT) complex, prothrombin fragment 1 + 2 (PF1 + 2), and fibrinogen levels were measured. Mean PC, f-PS, d-dimer, and fibrinogen values were similar at all periods for HPI and RDS groups. Low neonatal anticoagulant proteins increased within 6 months in HMI and HPI groups. However, in RDS group, the AT activity remained significantly lower together with significantly higher TAT and PF1 + 2 levels both at the first month and at sixth month, suggesting a long-term consumption coagulopathy.