Objective: The aim of this study was to evaluate the efficacy of REGENAMEL® on white spot lesions (WSLs)in terms of the extent of color change and the degree of mineralization.Materials and methods: Artificial white spot lesions were induced in 40 extracted human premolars, divided into a test and a control groups. REGENAMEL® was applied to the test group according to manufacturer's instructions, while the control group received no treatment. Both groups were incubated in remineralizing solution for 90 days at 37 °C. Specimens were evaluated using VITA Easyshade advance spectrophotometer at baseline (E0), after WSLs induction (E1) and 90 days following treatment (E2).DIAGNOdent evaluation was done After WSLs induction (D1) and at the end of incubation period (D2). Results: The Data was collected and statistical analyses were done using Statistical Package for Social Sciences (SPSS).No significant difference between groups was found after formation of WSLs ΔE (T0 -T1). Meanwhile significant difference was present between the two groups when comparing the color change after 90 days (T2-T1). ΔE values were 8.2 ± 4.81 and 1.92 ± 1.21 for the test and control groups respectively. Despite the final outcome showed marked improvement when compared to the baseline readings (T2-T0) 4.94 ± 3.66, the final color of the lesions was still not matching the baseline color. For the DIAGNOdent readings, at T1 the mean value for the test group was 15.55 ± 3.81 while that of the control group was 14.95 ± 2.16. At T2, for the test group, all specimens showed significantly decreased fluorescence values towards the values of sound dental tissues with mean value of 9.9 ± 1.94. The fluorescence values for the control group at T2 showed minimal change with mean value of 13.65 ± 2.03. Conclusion: REGENAMEL® is effective in improving the color of WSLs and remineralization of demineralized enamel surface.