Objective: Deep brain stimulation (DBS) is an effective treatment option for patients with refractory obsessivecompulsive disorder (OCD). However, clinical experience with DBS for OCD remains limited. The authors examined the tolerability and effectiveness of DBS in an open study of patients with refractory OCD. Methods: Seventy consecutive patients, including 16 patients from a previous trial, received bilateral DBS of the ventral anterior limb of the internal capsule (vALIC) between April 2005 and October 2017 and were followed for 12 months. Primary effectiveness was assessed by the change in scores on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) from baseline until the 12-month follow-up. Response was defined by a$35%decrease in Y-BOCS score, partial response was defined by a 25%234% decrease, and nonresponse was defined by a ,25% decrease. Secondary effectiveness measures were the Hamilton Anxiety Rating Scale (HAM-A) and the Hamilton Depression Rating Scale (HAM-D). Results: Y-BOCS, HAM-A, and HAM-D scores all decreased significantly during the first 12 months of DBS. Twelvemonths of DBS resulted in a mean Y-BOCS score decrease of 13.5 points (SD=9.4) (40% reduction; effect size=1.5). HAM-A scores decreased by 13.4 points (SD=9.7) (55%; effect size= 1.4), and HAM-D scores decreased by 11.2 points (SD= 8.8) (54%; effect size=1.3). At the 12-month follow-up, 36 of the 70 patients were categorized as responders (52%), 12 patients as partial responders (17%), and 22 patients as nonresponders (31%). Adverse events included transient symptoms of hypomania, agitation, impulsivity, and sleeping disorders. Conclusions: These results confirm the effectiveness and safety of DBS of the vALIC for patients with treatmentrefractory OCD in a regular clinical setting.