A few patients with obsessive-compulsive disorder (OCD) remain severely impaired despite exhausting best-practice treatments. For them, neurosurgery (stereotactic ablation or deep brain stimulation) might be considered. The authors investigated the proportion of treatment-seeking OCD patients, in a naturalistic clinical sample, who met contemporary neurosurgery selection criteria. Using comprehensive baseline data on diagnosis, severity, and treatment history for adult patients from the NIMH-supported Brown Longitudinal OCD Study, only 2 of 325 patients met screening criteria for neurosurgery. This finding prompts consideration of new models for clinical trials with limited samples as well as methods of refining entry criteria for such invasive treatments.