The authors report the case of a neonate, a premature 36 weeks gestation male child who presented with a spontaneous thrombosis of the juxtaduetal aorta at 3 days of age. The clinical presentation mimicked that of severe coarctation with cardiocirculatory failure. The diagnosis was ineffective, the introduction of low dose alteplase (plasma activator of human recombinant plasminogen) with continued anticoagulation resulted in near complete lysis of the clot and avoided surgery. Thromboembolic cerebral and renal complications were observed during treatment. However, 6 months after the acute episode, there were no clinical or echographic sequellae. Global renal function remained normal despite mild atrophy of the parenchyma of the left kidney. This combined treatment represents an alternative to high risk surgery. The follow-up of this form of management should be rigorous in view of the potential renal and cerebral complications.