<jats:title>Abstract</jats:title><jats:p>Four new cyclic heptapeptides, stylissamides A–D (<jats:bold>1</jats:bold>–<jats:bold>4</jats:bold>), were isolated from the Caribbean sponge <jats:italic>Stylissa caribica</jats:italic>. The structures of these metabolites were elucidated by NMR and MS/MS methods. The peptides contain three and, in one case, four proline residues. The sequence assignment of <jats:bold>1</jats:bold>–<jats:bold>4</jats:bold> by NMR was supported by fragmentations in HR‐MS/MS measurements. The absolute configuration of all amino acid residues was assigned as <jats:sc>L</jats:sc> using Marfey's method and the OPA method.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)