Study design: Two case reports of aseptic meningitis after intrathecal baclofen injection. Objectives: To report an unusual complication of intrathecal baclofen injection during test injections. Setting: Department of Neurological Rehabilitation, R Poincare´Hoˆpital (Paris-Ile de FranceOuest University). Case reports: We present two cases of chemical meningitis after intrathecal baclofen injections by lumbar puncture. These cases presented with febrile meningeal syndromes during the 24 h following intrathecal baclofen injection. Direct cerebrospinal fluid (CSF) examination and CSF cultures were negative. An intense cellular reaction was observed with a marked predominance of neutrophils. Meningitis resolved spontaneously over 3-4 days. Conclusions: Chemical meningitis is a rare complication of intrathecal baclofen injections that must be recognized. It is a diagnosis of exclusion and its pathophysiological mechanism remains unclear.