Investigation of aqueous methanol extracts of the cyanobacterium Nodularia spumigena KAC 66 led to the isolation of the nodulopeptins 899, 901 and 917. The chemical structures were determined using highresolution NMR and MS-data. The stereochemistry of the amino-acid residues was realized by LCeMS analysis using Marfey's reagent. The bioactivity of the novel compounds was determined.