Current treatment outcomes for obsessive-compulsive disorder patients are far better than in past decades, but variability in treatment response remains. Most obsessive-compulsive disorder patients, but not all, respond to antidepressant agents with prominent serotonin uptake blocking properties. Because clomipramine's usefulness is limited by side effects which often accompany its use, a considerable degree of attention has shifted to selective serotonin reuptake inhibitors. A number of studies have also provided evidence for the effectiveness of medication other than those mainly involving serotonergic function, either as augmenting agents or for comorbid disorders. Neurosurgery may be useful for highly selected subjects.