The lichen Roccella sinensis has not been studied chemically. This research described the isolation and elucidation of compounds isolated from the lichen Roccella sinensis collected in Binh Thuan. Phytochemistry investigation of this lichen was carried out by using normal phase silica gel column chromatography and thin-layer chromatography. Six compounds was isolated. Their structures were established by extensively spectroscopic analysis as well as comparison with NMR data in the literatures. They are (+)-D-montagnetol (1), (+)-D-erythrin (2), lecanorin (3), 1-acetylerythritol (4), (E)-nostodione A (5), and 2,4-dihydroxyphthalide (6). This is the first time compounds 3 6 were found in the Roccella genus. Compounds 1, 2, and 6 were evaluated for their cytotoxic activities against HepG2 (liver hepatocellular carcinoma), NCI-H460 (human lung cancer), MCF-7 (human breast cancer), and HeLa (human epithelial cancer) and all of them showed no activity.