Since clinical and biological 'markers' in depressive disorders are missing, the antidepressive drug choice today is based on several classifications. The chemical classification separates antidepressive drugs according to their structure. Their activity mechanism and/or specificity on brain neurotransmittors constitute the biochemical classification. Their sedative, median or stimulating activity provide the therapeutic classification. Which criteria should be used in choosing? The choice depends on clinical and biological data obtained from the patient. Chemical classification may be useful at a new molecule synthesis level. In the biochemical classification, anticholinergic and antihistaminic activities inducing side effects and sedation are taken in account. The therapeutic classification is usually used first, especially in case of first cure. An antidepressive drug will be prescribed according its initial effects on anxiety or holding up, facilitating the wait for its antidepressive action. A better definition of samples studied and of study aims, and improvement in knowledge about activity mechanisms of antidepressive drugs might provide answers regarding treatment choice in depressive disorders.