During the past years, studies dealing with the pathophysiology of brain injuries have focused on certain agents that seem to be particularly involved in secondary brain lesions. Of them, some amino acids, and particularly glutamate, appears to deserve special attention. We discuss the role of glutamate neurotransmitters, review glutamate metabolism and actions, and then review in the pertinent literature devoted to the role of glutamate in the onset of brain injuries secondary to head trauma.