OBJECTIVE: To evaluate the long-term effects of deep brain stimulation (DBS) on quality of life (QOL) in therapy-refractory obsessive-compulsive disorder (OCD) patients. DESIGN: 16 patients who met Diagnostic and Statistical Manual of Mental Disorders (4th ed) (DSM-IV) criteria for OCD and were considered therapy-refractory were treated with DBS. Patients were assessed 1 month before device implantation (T0), at 8 months of active stimulation (T1) and at 3-5 years of active stimulation (T2). QOL was measured with the WHO Quality of Life Scale-Brief Version (WHOQOL-BREF) that covers physical, psychological, social and environmental domains. The study was conducted between April 2005 and January 2011 at the Academic Medical Center, Amsterdam, The Netherlands. RESULTS: At T1 and T2, we found significant improvement (p