<jats:p>Gallidermin is a new member of the class of lanthionine‐containing peptide antibiotics, which are summarized under the common name lantibiotics. The lantibiotic gallidermin is produced by <jats:italic>Staphylococcus gallinarum</jats:italic> (F16/P57) Tü3928, and it exhibits activities against the Propionibacteria, involved in acne disease. Gallidermin differs from the recently discovered tetracyclic 21‐residue peptide antibiotic epidermin only in a Leu/Ile exchange in position 6. The isolation procedures for gallidermin included adsorption directly from the culture broth, ion‐exchange chromatography of the amphiphilic and basic polypeptide followed by desalting, and final purification by reversed‐phase HPLC. The structural elucidation of the polypeptide containing four thioether bridges involved mainly a combination of automated gas‐phase sequencing, thermospray liquid chromatography/mass spectrometry and fast‐atom‐bombardment mass spectrometry.