In 1979, a man was poisoned when he ate a trumpet shell, Charonia sauliae, in Shimizu, Shizuoka Prefecture. The causative agent was later identified as tetrodotoxin (TTX).1* Most of the specimens of trumpet shells collected off Shimizu contained TTX in the digestive gland, the highest toxicity2) being 1,950 mouse units (MU)*1 per gram. This species is a large gastropod inhabiting the Pacific coasts of western Japan. It feeds on various kinds of benthic animals, and prefers echinoderms such as starfish and sea urchins. We found that a starfish, "togemomijigai," or Astropecten polyacanthus, remains of which are often found in the digestive tract of trumpet shells, contained TTX.3) We found paralytic toxicity in another starfish, "momijigai," or Astropecten scoparius (Fig. 1), and undertook this study. A total of 16.5kg of Astro, scoparius was collected off Shimizu in May 1981 and kept frozen below -20°C until use. The specimens were homogenized in 3 volumes of 1% acetic acid in methanol, and centrifuged at 3,000 rpm for lOmin. This procedure was repeated for the residue two more times. The extracts were combined, evaporated in vacuo, and defatted with dichloromethane. The aqueous layer (total toxicity; 10,200MU) was concentrated to 700ml, adjusted to pH 5.2 with In NaOH, and treated batchwise with 500g of activated charcoal (Wako). The charcoal was washed with water and then the toxin adsorbed was eluted with 1% acetic acid-20% ethanol (6,800MU). The eluate was evaporated to dryness in vacuo. The solid obtained was dissolved in 70ml of water and put on a column (5x23cm) of Amberlite IRC-50 (NH^ form). The column was washed with 600ml of