Antipsychotics play a key role in the pharmacological treatment of schizophrenia, and monotherapy is effective for most patients. Achieving an optimal treatment response is, however, often difficult. Combining an antidepressant drug to the antipsychotic regimen could potentially improve treatment outcomes, although the evidence supporting the use of such combinations is limited and contradictory. Positive evidence has mostly been obtained from the efficacy of antidepressants acting on monoamine receptors on the negative symptoms of schizophrenia. These receptor-active drugs may also improve cognition in schizophrenic patients. In the light of current knowledge, antidepressants do not appear to potentiate the psychotic symptoms of schizophrenic patients. However, there is no robust evidence of the efficacy of antidepressants in the treatment of schizophrenia-related depression, and thus monotherapy with an antipsychotic drug is recommended for treating it. If using antidepressants in addition to antipsychotics is deemed necessary, the risk of pharmacodynamic and pharmacokinetic interactions should be kept in mind.