Three new epipolythiodioxopiperazines, chaetocochins A (1), B (2), and C (3), along with dethio-tetra (methylthio) chetomin (4) and chetomin (5), were isolated from the ethyl acetate extract of the solid-state fermented rice culture of the fungus Chaetomium cochliodes. Their structures were elucidated on the basis of spectroscopic analysis. Compounds 1, 3, and 4 exhibited significant cytotoxicity in vitro against cancer cell lines Bre-04, Lu-04, and N-04.