A patient with valproic acid induced hyperammonaemic
encephalopathy is presented. During chronic treatment
with valproic acid this patient developed a potentially
life-threatening encephalopathy without signs of liver
failure. After discontinuing the valproic acid the patient
recovered completely. In the case of a patient presenting
with hyperammonaemic encephalopathy, the possibility of the use of valproic acid should not be overlooked.