A double blind, randomized, controlled study with three parallel treatment groups was done to evaluate the efficacy of a Terminalia chebula 10% mouth rinse compared with chlorhexidine 0.12% mouth rinse, applied two times daily for 2 weeks, in the treatment of dental plaque and gingivitis. Seventy-eight patients were included in the study. The efficacy variables were periodontal indices on days 0, 7 and 14 after commencement of therapy. Twenty six patients received chlorhexidine mouth rinse, twenty six Terminalia chebula mouth rinse and twenty six received saline solution. The clinical parameters were significantly reduced by both chlorhexidine and Terminalia chebula mouth rinse although no significant difference was seen between the two groups (P > 0.05). This study demonstrated that Terminalia chebula mouth rinse is effective in reducing microbial plaque, gingival inflammation and neutralizing salivary pH. Copyright © 2013 John Wiley & Sons, Ltd.