Objectives: To assess the efficacy of Thymus vulgaris (T. vulgaris) essential oil to decrease the count of Candida albicans (C. albicans) accumulated on removal orthodontic appliances.Methods: In this 2 arm parallel controlled clinical trial, Forty-four patients whose removable orthodontic appliances contaminated with C. albicans were randomly divided into two groups for use of T. vulgaris essential oil and 0.2% Chlorhexidine (CHX) by electronic random sampling. The C. albicans colony count was measured at baseline (T0) and at 2 (T1) and 5 (T2) days after the intervention. Microbial samples were collected by a sterile swab from 3 spots on the internal surface of orthodontic appliances. The Friedman test was used for within-group comparisons while the Mann Whitney test was applied to compare the efficacy of T. vulgaris essential oil and CHX.Results: No significant difference was noted in the efficacy of 2% T. vulgaris essential oil and 0.2% CHX in decreasing the C. albicans colony count on removable orthodontic appliances.Conclusion: T. vulgaris essential oil has favorable antimicrobial activity against C. albicans.