Trichocadinins B-G (<b>1</b>-<b>6</b>), six new cadinane-type sesquiterpene derivatives, each with C-14 carboxyl functionality, were isolated from the culture extract of <i>Trichoderma virens</i> QA-8, an endophytic fungus obtained from the fresh inner tissue of the medicinal plant <i>Artemisia argyi</i>. Their structures were elucidated by interpretation of the NMR spectroscopic and mass spectrometric data. The structures and absolute configurations of compounds <b>1</b> and <b>3</b> were confirmed by X-ray crystallographic analysis. Compounds <b>1</b>-<b>3</b> showed antibacterial and antifungal activity.