Obsessive-compulsive disorder (OCD) constitutes an etiologically heterogeneous set of conditions, including a subtype that seems etiologically related to Tourette syndrome (TS). In order to treat OCD patients optimally, the clinician needs to integrate educational, psychological and pharmacological approaches. The most effective psychological intervention is cognitive-behavior therapy (CBT). Drug treatment includes clomipramine and all selective serotonin reuptake inhibitors (SSRIs). A subgroup of OCD patients, however, shows no significant improvement. Few studies suggest that the presence of tics is associated to a worse treatment response to SSRIs and that such patients benefit from combined therapy of serotonin-reuptake inhibitors plus neuroleptics. Independently of the presence of tics, there are several different augmentation strategies for resistant cases with drugs that interfere in the dopamine, serotonin, opioid and gonadal hormone systems. In addition, new therapies are now being tested against presumed postinfectious autoimmune processes. Finally, new developments are promising in neural circuit-based therapies, including neurosurgery for refractory patients.