 Obsessive-compulsive disorder OCD is a relatively common psychiatric condition, which is classically treated by antidepressant medications in combination with psychotherapies. However, both these conventional therapeutic approaches fail to sufficiently improve obsessive-compulsive symptoms in 20-30 of cases. From these considerations, deep brain stimulation DBS, as a reversible and adjustable surgical procedure, has recently been introduced in the field of resistant OCD. DBS currently uses electrodes with four contacts on each lead, which are bilaterally implanted into the chosen brain structure. DBS consists of the delivery of a high-frequency current through the quadripolar electrodes connected to a battery powered pulse-generating device. Several clinical investigations have shown that DBS, primarily targeting either the ventral striatum VS or the subthalamic nucleus STN, as brain sites of interest because of their particular involvement in the production of OCD symptoms, is able to produce an approximately 40 or greater reduction in clinical symptom intensity in severely chronic and incapacitating forms of OCD. These promising findings lead to propose a comparison of the efficacy, safety and tolerability of DBS choosing either the VS or STN as brain target by conducting a large controlled trial and including a medico-economic analysis for assessing the classical costefficacy ratio. In this way, the present study is expected to promote and highlight the importance of DBS, as an effective, safe, well-tolerated and cost-relevant surgical approach for the management of resistant OCD. 