Purpose: Triphala is an ayurvedic preparation with known antimicrobial action. This study was carried out to assess the antibacterial efficacy of triphala against salivary mutans streptococci in comparison with the 'gold standard' chlorhexidine. Materials and Methods: A double blind randomised control trial was conducted among 57 volunteers who were assessed to be in the high caries risk category. They were randomly allocated into three study groups: 1) 15 ml of 6% triphala mouthwash; 2) 15 ml of 0.2% chlorhexidine (active control); 3) no mouthwash (passive control). Mouthwashes were given twice a day for 15 days. Unstimulated saliva samples were collected at baseline and at 15 and 45 days. Mutans streptococci (MS) were cultured on MSB agar and colony counts obtained. The α error was fixed at 5%. ANOVA and post-hoc LSD tests were performed using SPSS version 14. Results: After using mouthwash for 15 days, an 83% and 80% reduction and at 45 days a 67% and 65% reduction in salivary MS colony count was observed in the triphala and chlorhexidine groups, respectively (P = 0.0001). The control group showed an increase of 3% in MS colony count at 15 days and a reduction of 7% at 45 days. (P = 0.116). Conclusion: The antimicrobial action of triphala against mutans streptococci closely parallels that of chlorhexidine. It does not have the side effects commonly associated with chlorhexidine and is cost effective. Keywords: chlorhexidine, dental caries, mutans streptococci, triphala