So this study is to appraise the efficacy and safety of the combination of fluoxetine-olanzapine in patients with depression at outpatient clinic in Ho Chi Minh City Mental Hospital from 20/09/2009 to 20/10/2010. Subjects and Methods: a prospective, open and non-comparative study design, in 43 patients diagnosed with major depressive disorder according to DSM-IV-TR criteria, treated with fluoxetine combination of olanzapine at outpatient clinic of Ho Chi Minh City Mental Hospital. Using HAM-D 17 scale to monitor treatment responses, side effects of the combination in the 4-week treatment period.