The structure of brevigellin, a new cyclodepsipeptide isolated in small amount from Penicillium brevicompactum is elucidated from chemical evidence and analysis of NMR and high resolution mass spectra. The aminoacid residues consist of N-benzoythreonine, alanine, proline, a novel aminoacid postulated as 3-(3carboxypropyl) A*-pyrroline and β-aminobutyric acid.