Describing new brain structures may open research avenues and improve our knowledge of brain functions and of brain disorders. It may also provide new neuroanatomical targets for treatments. A detailed understanding of neuroanatomy is a prerequisite of understanding the pathomechanisms underlying psychiatric disorders on a molecular and cellular level. The tail of the ventral tegmental area (tVTA), also known as rostromedial tegmental nucleus (RMTg), is a recently described region which may be a major inhibitory control centre for the dopaminergic systems. These systems participates to behavioural functions and are implicated in the aetiology, symptoms or treatment of neurological or psychiatric diseases, such as Parkinson's, schizophrenia, mood disorders, attention-deficit hyperactivity-disorder (ADHD) and drug abuse. Belonging to the reticular formation, the tVTA may constitute a major inhibitory GABAergic input to these dopaminergic systems. Moreover, it is sensitive to drugs of abuse, to stimulant or arousing drugs, to aversive stimuli and it could also be the main relay between lateral habenula and VTA. First described in rats, and proposed as a component of the emotional motor system implicated in basic survival behaviours, tVTA appears as a relevant structure for molecular psychiatry, which should foster research to define and study this brain region in the human brain.