The structures of two phytotoxins, syringomycin and syringotoxin, produced by Pseudomonas syringae pv. syringae, were determined. Several amino acid residues of syringomycin were different from those in the syringostatins. Syringotoxin B proved to be [Gly³]syringostatin A. The three kinds of phytotoxins showed close structural similarity, and the stereochemistry of their components was deduced and compared.