The Knowledge of the antibiotic's cerebral diffusion is essential to define a of neurosurgical antibioprophylaxis' strategy. Without references in the medical world-literature, we've decided to compare the pharmacological kinetics in the blood, the cerebrospinal fluid and the sound cerebral tissue of common used molecules in neurosurgery that is to say: amoxicillin, cefamandole, metronidazole and pefloxacin. The results show that the cerebral levels of metronidazole and pefloxacine are rapidly high with an extended duration (> 10 times the M.I.C. of the sensitive bacteriae), but the tissue penetration of amoxicillin is hazardous and shot-duration for cefamandole (undosable after 3 hours).