Mood disorder is a medical illness resulting from the disorder of CNS neurotransmission and its principal therapeutic tool is pharmacotherapy. Psychotherapeutic drugs for mood disorder have some clinical limitations which are due to no or partial response, decreased compliance for drug by the side effects, and delayed therapeutic effects. So, general hope of all clinicians that mood diorder will respond to a single psychotherapeutic agent may be the exception rather than the rule. Recently, combined drug treatments have become increasingly popular to overcome the clinical limitations of individual agent in mood disorder. Combined treatments are usually used for augmenting or initiating rapidly the effect of drug, and for treating different target symptoms or drug side effects. When combined treatments being tried, knowledge of the action mechanism, pharmacokinetics, and pharmacodynamics is crucial to cope with the possible adverse reactions of drugs.