We have used the microdialysis equipment described above since more than 4 years and performed more than 100.000 bedside biochemical analyses in more than 100 patients. The ordinary nurses and assistant nurses have performed all the biochemical analyses bedside. No complications or side effects have been observed.This report shows that intracerebral microdialysis with bedside biochemical analyses (glucose,pyruvate,lactate,glycerol,glutamate,and urea) can be performed as a routine procedure during neurosurgical operations and neuro intensive care. The technique and instrumentation presented are standardized and will allow comparison of data from different centers. The normal values for the metabolites here described will serve as reference values for the interpretation of the changes observed during microdialysis in patients with traumatic brain injury or hemorrhage.