PurposeThis in-vitro study evaluated and compared the effect of white henna (WH) and natural henna (NH) addition on Candida albicans adhesion and physical properties of the denture base material. Materials and MethodsA total of 243 acrylic resin specimens (9 per group) were divided as follows: 81 for flexural strength, 81 for Candida albicans adherence test, and 81 for surface roughness, translucency, and hardness. Heat-polymerized acrylic resin specimens were prepared by adding 0.5, 1.0, 1.5, or 2.0 wt% of WH or NH. Candida albicans adhesion was determined using direct culture and slide count methods. Flexural strength, surface roughness, hardness, and translucency were measured using the three-point bending test, profilometer, Vickers hardness test, and spectrophotometer, respectively. ANOVA and post hoc Tukey's tests were performed for data analysis. ResultsAddition of 0.5% WH, 1% WH, and 0.5% NH to denture base resin significantly decreased Candida albicans adhesion (p<0.05). WH and NH significantly decreased the flexural strength and translucency, except 0.5% WH, and significantly increased surface roughness, except 0.5% WH and 0.5% NH. WH addition showed nonsignificant differences in the hardness, while NH addition significantly decreased hardness (p<0.05). ConclusionAddition of WH and NH decreased C. albicans adhesion to PMMA denture base resin. However, flexural strength, translucency, and surface roughness were adversely affected, particularly at higher concentrations. Hardness was reduced with NH only.