Abstract： Objective To determine the contents and dynamics of excitatory amino acids (EAAs), glutamate (GLU) and aspartate (ASP) in the cerebrospinal fluid (CSF) of patients with acute head injury and to clarify the relationship of EAAs with clinical features and outcomes.Methods Forty-two adults with acute head injury were included. Glasgow coma scale (GCS) obtained at admission and Glasgow outcome scale (GOS) obtained three months post-injury were assessed. Samples of CSF were obtained via ventricular or lumbar puncture every 24 hours. GLU and ASP in CSF were analyzed by reversed-phase HPLC with a fluorescent detector. Nine control subjects were adults with lumbar anesthesia but without neurological diseases.Results The peak concentration of GLU and ASP of head-injured group was significantly higher than that of the control group. Dynamic research on severely injured ones indicated that the peak value of GLU mostly appeared within 48 hours post-injury; it decreased with the improving or remaining of the neurological status, and increased with the deterioration, but was still higher than that of the control seven days post-injury. The peak value of EAAs of severely injured patients was conspicuously higher than that of mildly injured group. There was a significant negative correlation between the peak values of GCS and EAAs. The peak value of EAAs in patients with poor outcome was remarkably higher than that in patients with good outcome. GOS was closely correlated to the peak value of EAAs. When the concentration of GLU was over 7 μmol/L, the rate of poor-outcome increased markedly. Conclusion The content of EAAs in CSF increases following acute head injury and remains higher at least a week post-injury in severely injured patients. The more severe the trauma, the more obvious the excitotoxicity induced by EAAs; the more serious the secondary brain insult and the brain edema will be, the worse the outcome, naturally.