Obsessive Compulsive Disorder (OCD) is a disease that affects 2-3% of the population with high comorbidity and a negative impact on the person overall functioning. About 30% of patients have severe and persistent symptoms despite the combination of pharmacological and psychotherapeutic treatments. In these cases, deep brain stimulation (DBS) of the subthalamic nucleus allows both the reduction of symptoms severity and the improvement in overall functioning. A clinical case is presented by integrating the latest data research to show not only the result of DBS therapy but also its contribution to a better understanding of the pathophysiology of OCD.