A large number of coagulation abnormalities have been described in SCD. Thus, activation of coagulation has been shown to be a feature of this disorder, both in the steady state and during painful crisis, with rates of thrombin and fibrin formation constantly higher than normal. In this study we determined the levels of several coagulation pathway parameters in 38 children and adolescents with SCD during steady state, and in 16 during thrombotic crisis. In patients during steady state we found significantly increased levels of D-dimers, and decreased levels of A2-antiplasmin, compared with healthy controls. In patients during thrombotic crisis we found significantly increased levels of D-dimers and VWF, and decreased levels of TT, compared with healthy controls and patients in steady state. These findings confirms the serious dysfunction of coagulation pathway during thrombotic crisis, while pathologic values in some of them during steady state shows the presence of chronic inflammation and activation of coagulation in SCD patients.