Phenytoin Sodium (Sodium diphenylhydantoinate) is established in the treatment of epilepsy. Toxic side effects, especially on the nervous system, have been well documented. Untoward reactions may follow therapeutic doses taken over a period of time, or as the result of a single massive dose taken accidentally or with suicidal intent.The following case of toxic reaction is reported because of the unusual mode of presentation and the associated C.S.F. changes.