OBJECTIVE: To evaluate the changes in the plasma levels of thrombomodulin (TM), tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PA1-1) as indices of endothelial injury/activation and fibrinolysis in childhood Henoch-Schonlein purpura (HSP). METHODS: Twenty-six children with HSP aged between 4-15 years and 10 healthy controls were included in the study. Blood samples were taken from these patients at admission and 6-12 weeks after healing of skin rash and arthritis. Plasma levels of TM, t-PA and PAI-1 activities and t-PA and PAI-1 antigen (Ag) levels were measured. RESULTS: The plasma levels of TM, t-PA Ag and PAI-1 Ag in patients during the acute phase were significantly different from the controls. The difference in TM between the acute phase and recovery in patients was also significant. The decrease in plasma levels of t-PA Ag and PAI-1 Ag in patients between the acute and recovery phases was not significant. t-PA activity was significantly higher in the acute phase than in the recovery phase. CONCLUSION: We suggest that increased levels of TM, t-PA, and PAI-1 activity may reflect the presence of endothelial injury and/or activation and fibrinolytic activation in patients with HSP.