We examined the effect of the novel atypical antipsychotic drug aripiprazole alone or in combination with the selective serotonin reuptake inhibitor fluoxetine in the mouse tail, Suspension test. We also investigated the effect of aripiprazole on glucose metabolism. Combined treatment with aripiprazole and a sub-effective dose Of fluoxetine significantly decreased the duration of immobility in the tail suspension test. Aripiprazole by itself did not affect the duration of immobility. While olanzapine significantly increased blood glucose level in the glucose tolerance test, aripiprazole did not affect glucose metabolism. We suggest that aripiprazole augments the antidepressant-like effect of fluoxetine without affecting glucose metabolism.