Background: Neurosurgery (anterior capsulotomy) has been beneficial to many patients with debilitating, refractory obsessive-compulsive disorder (OCD), but the irreversibility of the procedure is an important limitation to its use. Nondestructive, electrical stimulation (deep brain sti mulation; DBS) has proven an effective alternative to ablative surgery for neurological indications, suggesting potential utility in place of capsulotomy for OCD. Methods: The effects of DBS for OCD were examined in four patients in a short-term, blinded, on-off design and long-term, open follow-up. The patients had incapacitating illness, refractory to standard treatments. Hardware developed for movement disorder treatment was surgically implanted, with leads placed bilaterally in the anterior limbs of their internal capsules. Patients received stimulation in a randomized "on-off" sequence of four 3-week blocks. Ongoing, open stimulation was continued in consenting patients after the controlled trial. Results: Patients tolerated DBS well. Dramatic benefits to mood, anxiety, and OCD symptoms were seen in one patient during blinded study and open, long-term follow-up. A second patient showed moderate benefit during open follow-up. Conclusions: It appears that DBS has potential value for treating refractory psychiatric disorders, but additional development work is needed before the procedure is utilized outside of carefully controlled research protocols. © 2005 Society of Biological Psychiatry.