OBJECTIVE To compare the antiplaque, antigingivitis and antibacterial efficacy of chlorhexidine (CHX), XYL and a mouthwash combining CHX and XYL against Streptococcus mutans (S. mutans). METHODS A parallel design, randomised controlled trial was conducted among 75 dental students. Participants were randomised into CHX, CHX+XYL and XYL-only groups using the lottery method. Subjects were instructed to use 10 ml of the provided mouthwash for 15 s twice daily for 3 weeks. All the outcome measures, gingival index (GI), plaque index (PI) and number of salivary S. mutans CFU were recorded at baseline and 3 weeks post intervention. Nonparametric tests were used for inferential statistics. RESULTS All outcome variables (GI, PI scores and log10 salivary S. mutans counts) decreased significantly from baseline compared to post intervention among all three groups. Intergroup comparison demonstrated that reduction in GI was not significantly different among the three groups. The decrease in PI scores was found to be significantly higher in the XYL group, while the decrease in the log10 salivary S. mutans count was significantly higher in the CHX+XYL group. CONCLUSIONS The present study provided sufficient data to suggest that all the three mouthwashes are effective against plaque, gingivitis and S. mutans load in saliva. Further investigations should be carried out to confirm the results and develop strategies for using such products to prevent tooth decay.