Introduction: The prevalence of dental caries in Indonesia reaches 88.8%, and the province of South Kalimantan ranks second with rate of 86.9%. Streptococcus mutans is the main etiologic causing dental caries, because it can form biofilms. Streptococcus mutans form biofilms by producing glucosyltransferase enzymes and matrix extracel- lular polymeric substances. Mauli banana is typical plant of South Kalimantan. Mauli banana stems are proven to have antibacterial and antifungal properties, but it is not yet known have antibiofilm properties. Methods: Antibiofilm potential was assessed based on percentage of remaining biofilm mass and percentage reduction in biofilm mass. This study used 10 groups, group 1 was given 0.2% chlorhexidine gel, group 2 wasn’t given treatment, group 3 was the media control, and group 4-10 was given Mauli banana stem gel with concentration of 6.25%, 12.5%, 25%, 37.5%, 50%, 62.5% and 75%. All groups were incubated 18 hours, then stained with crystal violet and observed using microplate reader. Results: The Mann-Whitney showed significant difference in all treatment groups. Conclu- sion: MBSG is an antibiofilm against the biofilm of S.mutans.