We report a case of a 42-year-old male who developed generalized tonic-clonic seizure with sudden, brief decrease in bispectral index (BIS) value while undergoing emergency kidney transplantation. Few reports have been made on intraoperative pitfall of BIS value associated with seizure. This case report suggests seizure should be taken into account as a reason for such brief fall of BIS, especially while under general anesthesia or in other specific cases in which clinical signs of seizure are unseen.