One case died of poisoning of tetrodotoxin in dry fugu fillet was reported. Through the detailed forensic examination for this lethal case, many questions about forensic medical identification of death due to poisoning of tetrodotoxin was discussed and its medico-legal significance was also discussed. In particular, emphasis was placed on the details of a case, extraction of TTX in specimen, quantitative detection of TTX, purplish mouth and nails, dilatation of stomach and intestines, excluding other causes and combining animal experiment in order to get definite forensic medical identification.