In order to arrive the small area in the deep brain with minimum invasion, stereotactic technique is useful. Subthalamic nucleus stimulation with this technique has been common for Parkinson disease. Recently some papers reported the cognitive performance change after implantation and there were some discussion about the electrode trajectory. Though we didn't have the answer until now, three-dimensional target included the trajectory seems to be important. Another way, stereotactic technique was used the epilepsy evaluation. The point of this procedure was based on the clinical aspect, the well-known neural network and the anatomical understanding for each patient. Three-dimensional anatomical target provides us the best treatment for stereotactic neurosurgery.