During the course of our research into the use of cane by-products from sugar manufacturing, we have studied the isolation and structural determination of bioactive compounds present in sugarcane molasses. In this study, dehydrodiconiferylalcohol-9'-O-beta-D-glucopyranoside (1) and isoorientin-7, 3'-O-dimethyl ether (2) were isolated as antibacterial active compounds against cariogenic bacteria. Their structures were elucidated by (1)H-NMR, (13)C-NMR and ESI-MS. The activities of these isolated compounds against Streptococcus mutans and Streptococcus sobrinus were assessed by a minimum inhibitory concentration (MIC) test. The MICs of compounds 1 and 2 against both S. mutans and S. sobrinus were >4 mg/mL and 4 mg/mL, respectively.