The present study investigated behavioral parallels between adaptation to stress and antidepressant treatment using the forced swim test. Restraint stress given repeatedly for 11 days significantly reduced immobility on this test. A single application of stress had no effect. The reduction in immobility produced by repeated restraint was quantitatively similar to that produced by repeated administration of desmethylimipramine. These results confirm previous findings of similarities in the behavioral and neurochemical response to chronic stress and chronic antidepressant treatment.