Introduction: Composite resin is a kind of tooth-colored restorative material that can be used for anterior and pos- terior teeth. Composite resins have several classifications including nanofiller composite resins which have good hardness, but acidic drinks such as lime (Citrus aurantifolia) can cause a decrease in the surface hardness of nanofill- er composite resins. This study aims to determine the effect of immersion of lime (Citrus aurantifolia) on the surface hardness of nanofiller composite resins. Methods: The number of samples in the study were 24 samples with a di- ameter of 5 mm and a height of 4 mm. Samples were divided into 2 groups: the control group immersed in distilled water and the treatment group immersed in lime (Citrus aurantifolia) which was carried out in an incubator at 370C to adjust to the normal temperature of the human body with 3 different time durations namely 3 days, 7 days and 11 days. After immersion, the sample is tested with Vickers Hardness Tester. Data were analyzed using One Way Anova test and Post Hoc Tukey. From the One Way Anova test it was concluded that there were significant results in the treatment and control groups. Results: The results of the Post Hoc Tukey test did not show significant results on day 3 and day 7, but there was a significant result on day 11. Conclusion: It can be concluded that there is significant surface hardness result of nanofiller composite resin on the immersion of lime (Citrus aurantifolia).