The Purpose of this study is to predict antidepressant response in advance using pharmacogenomics and peripheral biological markers in depressed patients.

The difficulties to treat depressed patients are 1)the patients don't respond to antidepressant is about 40% of which, and 2) The time lag is existed until the patients respond to antidepressant and show the treatment effects.

If it is predicted the response of antidepressant in advance, it would be overcome such problems. Drug response generally is known to be related to the individual genetic information and the environmental factors. We are going to investigation about antidepressant response using these approaches.

Inclusion Criteria:

1. 25 < age <85
2. major depressed patients satisfied with the diagnosis criteria depression of DSM-IV
3. interview with one more patient's family member for objective diagnosis and final diagnosis decision by agreements of two more psychiatric physicians

Exclusion Criteria:

1. received psychotropic medication within 2 weeks of the study or fluoxetine within 4 weeks
2. potential study participants for pregnancy, significant medical conditions, abnormal laboratory baseline values, unstable psychiatric features(eg.suicidal), history of alcohol of drug dependence, seizures, head trauma with loss of consciousness, neurological illness, or concomitant Axis I psychiatric disorder.