A 53-year-old man is treated by l-asparaginase for an acute lymphoblastic leukaemia. He received anti thrombin infusions. A systematic electrocardiogram showed an asymptomatic subepicardium ischemia without troponin elevation. Echocardiography and heart magnetic resonance imaging showed an apical thrombus facing a zone of myocardial necrosis. A thrombus regression was observed under anticoagulation. Atypical and asymptomatic coronary thrombosis may occur following l-asparaginase treatment. Regular electrocardiogram monitoring is proposed along this treatment. Arterial thrombosis associated with anti tumor chemotherapies are reviewed.