UNLABELLED: We measured levels of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) in 50 children and adolescents with β-thalassemia major (25 without hepatitis C virus [HCV] infection and 25 with HCV infection) compared to 25 healthy controls and assessed their relation to iron overload, HCV infection, and liver cirrhosis. Hematological and coagulation profiles, serum ferritin, and von Willebrand factor antigen were assessed. Levels of ADAMTS13 were significantly lower in β-thalassemia major with and without HCV infection compared to healthy controls, with a more significant reduction in levels among patients with HCV (P < .001). HCV-positive patients with thalassemia having liver cirrhosis had the lowest ADAMTS13 levels than those without cirrhosis (P = .012) or HCV-negative patients with thalassemia (P < .001). Levels of ADAMTS13 were positively correlated with platelet count while inversely correlated with partial thromboplastin time, serum ferritin, and VWF: Ag (P < .05). CONCLUSION: Patients with β-thalassemia major infected with HCV have low ADAMTS13 levels, and a marked reduction was observed among patients with liver cirrhosis and, therefore, may be liable to thromboembolic manifestations.