Surgery can be proposed for some patients affected by psychiatric diseases such as severe, disabling and refractory affective disorders (depression), OCD and chronic anxiety states. It can be performed after a period of evolution of minimum 5 Years and after all other classical treatments have failed. For the last Years, different stereotactic techniques have been used: capsulotomy, cingulotomy, subcaudate tractotomy and limbic leukotomy, performed by radiofrequency thermolesions or radiosurgery (g rays). In the case of OCD, these procedures are supposed to affect some of the neural circuits between the frontal lobes and different structures of the limbic system, considered as central to OCD symptoms. As they cause smaller cerebral lesions than earlier surgical techniques (mostly open surgery techniques), modern stereotactic approaches have less clinical side effects, primarily less deficit in emotional reactivity and motivation. This type of treatment offers some hope to patients seriously disabled by OCD. These surgeries and especially their main side effects are mentioned briefly in this Article. The most current indications for psychosurgery are severe OCD and chronic major depressive disorder. The level of stress should be significant and assessed by clinical and social functioning scale scores (for the OCD: Y-BOCS>25, GAF>50). Patients affected by demential disorders, sociopathic or paranoiac personality disorder, substance abuse should be excluded as well as patients aged 65 Years over and less than 18 Years. Several studies evaluating the results of the surgical treatment showed significant improvement in 54% of cases. and a moderate improvement in 27% of them. These results seem unchanged a few Years later in 56% of cases. Despite the lack of controlled trials of neurosurgery and several bias in published reports, evidence suggests that the condition of intractable OCD patients may improve after this surgery. Although capsulotomy and cingulotomy are mainly used, the superiority of any of these four surgical techniques has not been established yet. In this Article, we reported 3 "malignant" OCD cases treated by different psychosurgery techniques: 2 of the cases showed a clinical improvement, whereas the third did not -benefit from surgery. All of them were suffering of OCD since childhood with a gradual clinical impairment, unless the -second patient who presented a severe impairment following an accident causing a ten-day coma. In all three cases social consequences of OCD were important: negative socio-professional and family-life consequences and depressive complication with suicide risk. All patients remained unresponsive or showed a very transient reaction to the other forms of therapy, including varied pharmacotherapy (potentiation pharmacotherapy strategies included), intensive psychotherapy, behavioural therapy and electro-convulsive therapy. Pre- and post-operative assessment included neurological, radiological, psychometric and neuropsychological examination. The free and informed consent of the patient was always required before surgery, notifying the nature of the procedure, the potential risks and outcome. The first patient benefited of a bilateral anterior cingulotomy by thermocoagulation in stereotactic conditions, followed, four years later, by a second complementary one because of a relapse which occurred a few months after the first intervention. A clinical improvement was noticed over a period of two years, though it was not sufficient according to the patient. The second patient benefited of a stereotactic cingulotomy associated with a limbic leucotomy: it was initially efficient on OCD as well as on thymic symptoms. Nevertheless the positive evolution on OCD is not perceived by the patient and has not been assessed until now by clinical rating scales. Anterior cingulotomy is undergone in the third case, who showed a significant improvement. Despite clomipramine administered secondary to the surgery, a slight relapse of obsessive ideas was noticed six months later. The postoperative side effects were transient and regressive after a few months; they were observed especially in the case of tractotomy (oedema and transient frontal syndrome). On the whole, morbidity seemed more important with extensive lesions, whereas recurrence rate may be higher with smaller lesions. We did not observe any consequences on personality or on cognitive functions of these patients. No additional -deficits were observed after surgery. Further research is needed in order to determine the optimal site and size of the lesions in terms of efficacy and safety. Although psychosurgery is still controversial from an ethical view point, this treatment appears to be an ultimate solution for these severe disabled patients. Psychosurgery is a safe and relatively effective treatment which should be carried out by an expert multidisciplinary team in these disorders; surgery should be considered as part of an entire treatment program including an appropriate psychiatric rehabilitation part. Research in this field is currently focused on MRI-guided basal ganglia stimulation techniques which would allow to target specific structures in a reversible way.