Introduction: Food and drink consumption causes tooth discoloration, used of whitening agent could improving tooth brightness but had side effect. Teeth whitening using chemicals can cause side effects on the hard tissue of the teeth and soft tissue. Averrhoe bilimbil.L was chosen as an alternative material for natural teeth whitening because the oxalic acid content can whiten teeth. The aim of this study was to determine effect of cucumber tree gel (Averrhoe bilimbil.L) as a tooth whitening agent on enamel roughness in vivo. Methods: This study was experimental laboratory with 27 rabbits divided into 3 groups: 50% Averrhoe bilimbil.L gel, 40% oxalic acid gel, negative control group. Previous rabbit incisors were coated with transparent varnish in the specied area. Exposure to the use of bleaching material were carried out for 4 hours within 14 days. Enamel roughness analyzed by Surface Roughness Tester. Data were analyzed statistically (ANOVA and LSD test, P<0.05). Results: There was a significant increase in the value of enamel roughness after treatment with Averrhoe bilimbil.L gel(p=0.027). LSD-test showed no significant differences between Averrhoe bilimbil.L and negative control (p=0.104). Conclusion: Averrhoe bilimbil.L have potential act as tooth whitening agent with minimal sideeffect to enamel roughness in vivo.