Computer-assistance in coronary artery bypass grafting at the open heart with intraoperative navigation enables accurate placement of a bypass graft to a preoperatively planned anastomosis site. So far, navigation information were displayed on a monitor, requiring the operating surgeon to change focus from the monitor to the surgical site and vice versa during the navigation process. In this work, a mechanism is presented which is intended to enable the projection of registered preprocedural information directly onto the surface of the open heart. The method was tested on a heart phantom yielding good results.