In this paper, we describe a three-dimensional (3-D) display, containing a flat two-dimensional (2-D) display, an actuator and a half-silvered mirror. This system creates a superimposed slice view on the patient and gives accurate depth perception. The clinical significance of this system is that it displays raw image data at an accurate location on the patient's body. Moreover, it shows previously acquired image information, giving the capacity for accurate direction to the surgeon who is thus able to perform less-invasive therapy. Compared with conventional 3-D displays, such as stereoscopy, this system only requires raw 3-D data that are acquired in advance. Simpler data processing is required, and the system has the potential for rapid development. We describe a novel algorithm, registering positional data between the image and the patient. The accuracy of the system is evaluated and confirmed by an experiment in which an image is superimposed on a test object. The results indicate that the system could be readily applied in clinical situations, considering the resolution of the pre-acquired images.