Two novel metabolites of Penicillium paxilli were isolated and the structures determined, by mass spectrometry and 'H NMR spectroscopy, as 7c+hydroxy-13-desoxy paxilline and 10/l-hydroxy-13-desoxy paxilline. Chromatographically similar compounds were also recognized in fermentations of Acremonium lolii producing paxilline. Another indole-diterpenoid, 7r-hydroxy paxilline, which was apparently not tremorgenic, was characterized from P. paxilli, and recognized chromatographically in A. lolii in which it was shown by radiolabelling experiments to arise from transformation of the tremorgenic mycotoxin paxilline. The significance of the new compounds in biosynthetic interrelationships between the various indole-diterpenoid metabolites of Acremonium, Aspergillus, Claoiceps and Penicillium is discussed. Other notable aromatic amino acid-derived metabolites of A. lolii were tryptophol and tyrosol that were excreted from mycelia, the principal sterol of which was 5z-ergosta-7,22E-dien-3/?-ol.