The structure of FR900359, a novel cyclic depsipeptide from Ardisia crenata sims that shows inhibition of platelet aggregation and decrease of blood pressure, has been determined as 3-acetamido-22-benzyl-10- [1- [(3 hydroxy-4-methyl-2-propionamidopentanoyl)oxy]-2-methylpropyl]-4-isopropyl-7-(1-methoxyethyl)-19-methylene-8,13,14,16,20-pentamethyl-1,5-dioxa-8,11,14,17,20-pentaazacyclodocosane-2,6,9,12,15,18,21-heptone by hydrolytic, ¹H and ¹³C nuclear magnetic resonance spectroscopic, and mass spectrometric studies. FR900359 consists of ten units: alanine, N-methylalanine, β-hydroxyleucine (three residues), 3-phenyllactic acid, acetic acid, propionic acid, and the uncommon amino acids N-methyldehydroalanine and N,O-dimethylthreonine.