The present study was done to evaluate the antidepressant activity of ondansetron by using the these two animal models– a) Forced swimming despair test (porsolt‘s test) in mice, and b) Reversal of reserpine –induced ptosis in mice. The drugs used were Ondansetron ,Reserpine and Imipramine. In the forced swimming test, ondansetron significantly & dose dependently reduced the immobility period. Compared to imipramine it was less effective in reducing the immobility period.  In the reversal of reserpine –induced ptosis test, ondansetron significantly & dose dependently antagonized reserpine– induced ptosis. Compared to imipramine it was however less effective in antagonizing reserpine–induced ptosis.
          Taken together these two observations we suggest that ondansetron exerts antidepressant activity in animal models of depression