In established economies, mental disorders account for a larger burden of disease than all cancers combined. Yet reliable, measurable, markers of such diseases (biomarkers) are not uniformly known and without them, prediction that a new drug candidate makes contact with its target is poor. This is unfortunate because the attrition rate of new chemical entities (NCEs) in clinical development for CNS disorders is high and primarily driven by failure to show efficacy and often without knowing that the drug reached its intended target for action. Today, several companies have reported efforts towards the discovery of molecular biomarkers for CNS disorders. Confirmation, and ultimately validation of molecular (and other) biomarkers will hopefully foster new drug developments for multiple, currently poorly understood and inadequately treated CNS disorders.