A review of the world literature has failed to reveal any published reports of poststernotomy mediastinitis presenting as a deep neck infection. This article presents two such cases. Since the fascial layers of the mediastinum are a direct continuation of the cervical fascia, a number of potential pathways between the neck and mediastinum exist. Descending infection from the neck into the mediastinum is well documented. The reverse situation, an ascending infection from the mediastinum into the neck, is not described despite the potential natural pathways available for spread of infection. Our proposed mechanism for these two cases is that a surgically created pathway from the mediastinum to the lower neck allows for mediastinitis to point in the intercommunicating fascial spaces of the neck. Recognition of this clinical presentation will allow the surgeon to use prompt intervention for such a serious complication.