Attempts were made to identify the toxin in the gastropod Zeuxis samiplicutus that was responsible for the recent food poisoning incidents in southern Zhejiang, Mainland China. Symptoms associated with the poisonings included paralysis, coma, vomiting, and aphasia. The remaining specimens of gastropod were assayed for tetrodotoxin toxicity (TTX). The range of specimen toxicity was found to be 4 - 186 mouse units (MU), and the average toxicity was 111 +/- 45 MU. The toxin was partially purified from the methanol extract of the gastropod by ultrafitration and Bio-Gel P-2 column chromatography. Cellulose acetate membrane electrophoresis, TLC, and HPLC analyses demonstrated that the toxin contained TTX. It was concluded that the causative agent of the above food poisoning was TTX.