Six new quinone sesquiterpenes, myrothecols A-F (1-6), and hymenopsin B (7) were isolated from cultures of Myrothecium sp. SC0265 by bioassay-guided fractionation. Their structures were elucidated on the basis of 1D and 2D NMR and MS data. The absolute configurations of the new compounds were assigned by CD/TDDFT calculations, and that of and hymenopsin B was confirmed by X-ray diffraction analysis. Compounds 1-5 and hymenopsin demonstrated cytotoxic activity against human carcinoma A549, HeLa, and HepG2 cells. Compounds 1-5 also exhibited antibacterial activity against Staphylococcus aureus and Bacillus cereus.