A male adolescent developed a sinovenous thrombosis 4 weeks following a Henoch-Schonlein purpura episode. A hypercoagulation evaluation revealed a positive lupus anticoagulant. This suggests an association between Henoch-Schonlein purpura and antiphospholipid antibody syndrome and is the first report of sinovenous thrombosis after Henoch-Schonlein purpura that was likely due to elevated antiphospholipids. Children who develop Henoch-Schonlein purpura with neurologic features including headache should be evaluated for sinovenous thrombosis and a hypercoagulable state.