Thrombelastography (TEG) analyses the status of blood coagulation including abnormalities associated with low platelet count. The aim of this study was to investigate the changes in TEG parameters in idiopathic thrombocytopenic purpura (ITP) patients. Thirty nine patients with ITP (platelet count < 100 x 103 mu l(-1)) were included in the study. Age-matched 17 patients with thrombocytopenia due to chemotherapy were selected as a control group. Platelet count was positively correlated with maximum clot formation (MCF) in INTEM (r = 0.716, p < 0.001) and MCF in EXTEM (r = 0.679, p < 0.001); negatively correlated with clot formation time (CFT) in INTEM (r = -0.755, p < 0.001) and CFT in EXTEM (r = -0.585, p < 0.001) in ITP patients. Platelet count was positively correlated with MCF in INTEM (r = 0.776, p < 0.001) and MCF in EXTEM (r = 0.878, p < 0.001); negatively correlated with CFT in INTEM (r = -0.627, p < 0.001) in control group. Receiver operating characteristic curves to describe the critical platelet count and fibrinogen level that affect MCF revealed 31 x 103 mu l(-1) and 375 mg dl(-1) as cut-off values, respectively. In conclusion, ROTEM determines the contribution of fibrinogen and platelets to clot strength in patients with ITP. MCF appears to be the most important TEG parameter in predicting bleeding in ITP patients that makes TEG superior to other hemostatic tests.