Incidents of poisoning caused by edible marine bivalve, Tapes philippinarum in Kojedo, Korea were reported in March 1968 and 1969. The results of the present investigation revealed that the incidents were caused by hemorrhagic diathesis and liver injuries, as those caused by acute yellow atrophic liver. The minimal lethal dose of the liver extract of the bivalve varied with seasons. The dose was 0.02ml in March and increased to 0.25ml in April-May 1969. After lune the extract showed no toxicity. Phthalein reaction of smashed liver solution of the bivalve showed a great variation with seasons. In March the values of $P_1$(crude solution) and $P_2$ (boiled one) were 0.1 and 10, at its strongest toxicity. In May those of $P_1;and;P_2$ were 1 and 1,000. However the mouse died after intraperitoneal administration of 0.25ml of the liver extract at the $P_2$ value of 1,000. For this reason, determination of the toxicity is difficult by judging from the phthalein reaction alone. The bivalves collected from Pusan, Kaduk, Koje, Hansan, Yeosu, Mokpo and Kunsan were found nontoxic during April-August 1969.