Recent advances in the pharmacotherapy of obsessive compulsive disorder (OCD) have led to a significant reduction in suffering and a return to productive living for many patients previously considered refractory to treatment. Potent inhibitors of 5-hydroxytryptamine (5-HT) re-uptake clearly have been established as the first-line pharmacotherapy for treatment of OCD. The addition of agents that enhance 5-HT neurotransmission to ongoing treatment in patients whose OCD is refractory to 5-HT re-uptake inhibitors has not yielded impressive results. The addition of dopamine (DA) antagonists to the regimens of treatment-resistant patients appears to be a potentially useful strategy for the specific subgroup of OCD patients with a comorbid chronic tic disorder such as Tourette's syndrome. Pharmacologic studies suggest that both the 5-HT and DA systems may be critical to the treatment and possibly the pathophysiology of OCD.