New surgical tools, such as the exoscope, are being developed, and even skilled neurosurgeons need to learn the differences between an exoscope and a microscope. A middle cerebral artery aneurysm was clipped using an exoscope. Before clinical use, we simulated clipping by exoscope using model aneurysms. The characteristics of the position, quantity of light, and movement of the camera were recorded. Such simulation may be useful for new operative techniques.