Although significant progress has been made over the last decade in the treatment of obsessive-compulsive disorder (OCD), approximately 20% of OCD patients remain refractory to nonsurgical therapies, including pharmacologic and cognitive-behavioral therapy. Because a number of neural circuits involving the basal ganglia, thalamus, limbic system, and frontal lobes have been implicated in the pathophysiology of OCD, the need for an effective intervention in these patients has brought the focus on surgical approaches, including cingulotomy and capsulotomy procedures. Unlike free-hand surgical approaches used in the past, current neurosurgical interventions have been greatly enhanced by advances in technology, which allow lesioning to an accuracy of 1 mm. Today's neurosurgical approaches have shown significant benefit in as many as 60% of refractory patients, while preserving personality and cognitive functioning and limiting morbidity. A study of gamma knife capsulotomy conducted at Brown University School of Medicine showed that 40% of patients undergoing two lesioning procedures were much or very much improved 2 years postsurgery. The inherent obstacles to conducting placebo-controlled studies in these severely ill patients mean that further study is required to identify optimal candidates for surgical intervention.