Three new highly oxygenated eremophilane-type sesquiterpenes, 1 beta,10 beta(8,12)-diepoxy-7 beta,11 beta-dihydroxy-8 beta,12 alpha-dimethoxyeremophilane (1), 1 beta,10 beta-epoxy-7 beta-hydroxy-8 alpha-methoxyeremophil-11 alphaH-12,8 beta-olide (2), and 6 beta-isobutyryloxy-8 alpha-hydroxy-1-oxoeremophil-7(11),9-dien-12,8 beta-olide (3), together with nine known compounds (4-12) were isolated from the roots and aerial parts of Senecio nemorensis L. (Compositae). Structures of compounds 1-3 were elucidated on the basis of spectroscopic evidence including IR, HR-ESI-MS, 1D and 2D NMR techniques and were unequivocally confirmed by single-crystal X-ray diffraction experiments. The antimicrobial activity of the isolated compounds 1-3 and 8-12 was tested against Staphylococcus aureus and Candida albicans.