Anterograde amnesia, possibly accompanied by acute brain syndrome, is a potential side-effect of certain benzodiazepines, particularly triazolam. Flumazenil is a benzodiazepine antagonist that is highly effective in reversing the central nervous system effects of benzodiazepine overdose. We report a case of triazolam overdose resulting in anterograde amnesia after flumazenil administration had restored clear consciousness. The defect in memory may have been due to too little flumazenil being given or failure of memory consolidation affected by the character of triazolam during the induced lucent period. We feel that physicians should be aware of the potential occurrence of acute brain syndrome in patients with benzodiazepine overdose despite treatment with flumazenil.