Many studies (12-16) described the pharmacokinetics of oral and rectal acetaminophen in infants and neonates. Yet, the data on acetaminophen concentrations in the CSF is very limited. Two studies in adults (17;18) used intravenous propacetamol and described concentrations of acetaminophen in the plasma and CSF. Acetaminophen was detected as early as 15 minutes after the administration and reached peak concentrations in the CSF at the 4th hour. A small study (19) of nine children who had indwelling ventricular drains found that cerebrospinal fluid concentrations lagged behind those of plasma with an equilibration half time of 0.72 h. This study did not describe CSF concentrations in neonates and used a dose of 40mg/kg, which is higher than the recommended dose in children. To the best of our knowledge there is no data on acetaminophen CSF concentrations in neonates.