Almost 50 years after its discovery, valproic acid remains a mainstay in the treatment of epilepsy, both alone and in combination with other anticonvulsants. It is also associated with a hyperammonemic encephalopathy, when used in combination with other drugs. We present a case of valproate-induced hyperammonemic encephalopathy in a patient on multiple anticonvulsant and psychotropic medications. The patient presented with altered mental status and became progressively more obtunded and finally began to experience seizures. Her symptoms resolved with the discontinuation of valproic acid and with supportive care.