<jats:title>Abstract</jats:title><jats:p>Three new compounds, 2,4‐dimethoxy‐6‐methylbenzene‐1,3‐diol (<jats:bold>1</jats:bold>), salmoquinone (<jats:bold>2</jats:bold>), and 3‐(4‐hydroxyphenyl)‐4‐isobutyl‐1<jats:italic>H</jats:italic>‐pyrrole‐2,5‐dione (<jats:bold>3</jats:bold>), together with six known compounds, 2‐methoxy‐6‐methyl‐<jats:italic>p</jats:italic>‐benzoquinone (<jats:bold>4</jats:bold>), 2,3‐dimethoxy‐5‐methyl‐<jats:italic>p</jats:italic>‐benzoquinone (<jats:bold>5</jats:bold>), 2‐hydroxy‐5‐methoxy‐3‐methyl‐<jats:italic>p</jats:italic>‐benzoquinone (<jats:bold>6</jats:bold>), eburcoic acid (<jats:bold>7</jats:bold>), fomefficinic acid C (<jats:bold>8</jats:bold>), and a pyrroledione (<jats:bold>9</jats:bold>), were isolated from the mycelium of <jats:italic>Antrodia salmonea.</jats:italic> The structures of these compounds were elucidated by spectrometric analyses including IR, NMR, and MS. Among these compounds, <jats:bold>4</jats:bold> and <jats:bold>5</jats:bold> exhibited cytotoxicity against KB, HepG2, and H2058 cell lines.