The purpose of this study was to evaluate fluoxetine's efficacy in the treatment of major depressive illness met the criteria of DSM III R. The subjects were 20 patients receiving fluoxetine of 20 mg daily by 8 weeks. The psychic state was evaluated on the Hamilton Depression Rating Scale at the beginning and after 3, 6 and 8 weeks of the treatment. The course of the depression illness so far as its seriousness and the main symptoms were considered. Fluoxetine was the effective treatment for 13 of 20 patients. 3 patients were dropped out, l because of worsening and 2 because of severe insomnia. One patient did not respond and in 3 cases the respond was not sufficient. Prozac is recommended for the treatment of the depression syndrome of low intensity.