The authors measured the effect of different antidepressant drugs on the pineal production of melatonin in order to see if this test can be used in an antidepressants screening protocol. Six antidepressant drugs belonging to different pharmacologic classes have been tested. The results show that all the molecules used enhance the plasmatic and pineal concentration of melatonin. However the selectivity of this test must be reinforced by using classical methods for the detection of an antidepressant effect.