In the past serendipity and good clinical observation were essential for the discovery of new drug treatments for mental disorders. Today, neurochemical and pharmacological research allows development of compounds starting from hypothesis on the origin of the disorders and the actions of available drugs. The new compounds are cleaner from the pharmacological point of view, more specific and therefore with less undesired effects. Venlafaxine is one of these drugs and provides antidepressant efficacy in a broad range of depressed patients, including the most severe ones, with a good safety and tolerability profile.