In recent years, the role of serotonin in the pathophysiology of depressive disorders has been intensively studied. These studies have been complemented by the development of newer antidepressant agents that exert specific effects on serotonin systems. This paper reviews the pharmacology of these newer compounds and contrasts it with those of the standard tricyclic antidepressants. The current status of various serotonergic agents is discussed. Results are reviewed from recent double-blind studies comparing three compounds (trazodone, fluoxetine, and fluvoxamine) to a standard tricyclic antidepressant. Relative efficacy, dropout rates, optimal dosages, and side effects are emphasized. Data from studies on trazodone and fluoxetine suggest that lower dosages may prove as effective (if not more effective) than very high dosages. Implications of these data are discussed. Side effects of fluoxetine and fluvoxamine include primarily nausea, weight loss, insomnia, and anxiety. Possible application of specific serotonin reuptake blockers in the treatment of obsessive-compulsive disorder and in the reduction of alcohol consumption is also reviewed.