<jats:p>Extraction of the mycelium of the basidiomycete fungus Trametes feei grown on a synthetic medium has yielded ergosterol and a mixture of tetracyclic triterpenoid acids (26% of mycelial dry weight) which have been separated as their methyl esters. The major components have been shown to be polyporenic acid C (5a), 3-O-acetyltumulosic acid (6b), and a 1 : 1 mixture of tumulosic acid (6a) and dehydrotumulosic acid (5e): a minor constituent has been shown to be the new tetracyclic triterpene 6α-hydroxypolyporenic acid C (7d) by spectroscopic means and by conversion into derivatives of tumulosic acid.