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<0.05) in the general score and in the physical, psychological and environmental domains of WHOQOL-BREF. Between T1 and T2, the physical and psychological domains improved further (p<0.05). At T2, the general score improved by a total of 90%, the physical and psychological domains both improved by 39.5% and the environmental domain improved by 16%. The social domain did not change between baseline and follow-up assessments. Conclusions In line with symptom improvement, patient's QOL improved in the general score and in three of the four WHOQOL-BREF domains. This suggests that the improvement caused by DBS is not limited to symptom reduction alone, but also has a positive influence on patients' perception of their physical, psychological, environmental and global QOL.