The aim of the study was to evaluate the penetration of linezolid into cerebrospinal fluid (CSF) and brain tissue after a single i.v. dose of 600 mg. The penetration of linezolid into cerebrospinal fluid and brain tissue was studied in 18 patients undergoing a neurosurgical procedure. Linezolid 600 mg i.v. was given with the induction of anesthesia. Mean concentrations of linezolid 2h after the final dose, in serum, cerbrospinal fluid and brain tissue were assayed by HPLC. CSF/serum and brain/serum ratios were 69.57% and 44.66% respectively. Concentrations of linezolid were above the MIC(90s )for staphylococci and streptococci. The concentrations obtained indicate good penetration of linezolid into CSF and brain tissue and support its use in the management of multidrug-resistant Gram-positive CNS infections.