Two previously unknown red alkaloid pigments, mycenarubin A (1), and a dimer thereof, mycenarubin B (6), have been isolated from fruiting bodies of Mycena rosea and the structures of these pyrroloquinoline alkaloids have been established by 2D NMR and ESI-MS methods. Their absolute configurations were determined by comparison of their CD spectra with the CD spectrum of a synthetic model compound. The fungal pigments are structurally related to the damirones, isolated from a marine sponge, and may be biosynthetically derived from tryptophan and S-adenosylmethionine. ((c) Wiley-VCH Verlag GmbH & Co.