<jats:p>The structures of two new pyoverdins (GM-I and GM-II) isolated from the culture medium of Pseudomonas fluorescens have been elucidated by spectroscopic methods and degradation studies. The pyoverdins consist of a chromophore which could be identified as (1 S)-5-amino-2,3-dihydro-8,9-dihydroxy-1 H-pyrimido[1,2-a]quinoline-1-carboxylic acid substituted at the amino group with a 3-carboxypropanoyl or a succinamoyl residue and at the carboxy group with the N-terminus of D-Ala-D-Lys-Gly-Gly-D-threo-(OH)Asp-D-Glu-D-Ser-L-Ala-D-Ala-D-Ala-L-Ala-L-N<jats:sup>5</jats:sup>-(OH)Orn. <jats:p>According to the “short-hand” nomenclature proposed in [2]*** the two compounds should be characterized as pyoverdin-Q-akGGd'qsAaaAO′*-SUCA and pyoverdin-Q-akGGd'qsAaaAO′ *-SUC