Many patients fail to achieve an adequate response to antidepressant medication. Growing evidence suggests that atypical antipsychotics may augment antidepressant effects, resulting in a greater potential for response. Atypical antipsychotics possess pharmacological actions that are associated with antidepressant properties, including serotonin 5-HT(2) receptor antagonist and 5-HT(1A) and dopamine receptor partial agonist activity. In fact, the term 'atypical antipsychotic' is an unfortunate remnant of the early indication of these drugs in the treatment of schizophrenia. Soon after their introduction, the usefulness of atypical antipsychotics in bipolar disorder was firmly established and their use in the treatment of mood disorders has far outpaced their use in schizophrenia and other psychotic disorders. Aripiprazole has become the first agent to receive US FDA approval for the adjunctive treatment of unipolar depression. Most recently, Symbyax, a fluoxetine/olanzapine combination, received FDA approval for the acute treatment of treatment-resistant depression. This is the first medication to be FDA approved for this indication. In the present article, the usefulness of antipsychotics in the treatment of resistant unipolar depression is reviewed.