Objectives This in vitro study is designed to evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on microhardness and surface morphology of bleached enamel surface using 10 % and 15 % carbamide peroxide bleaching gel. Methods This study will involve a total of 40 premolars which will be divided into four groups (n=10) according to the bleaching agent used 10 % carbamide peroxide only, 10 % carbamide peroxide with CPP-ACP paste, 15 % carbamide peroxide only and 15 % carbamide peroxide with CPP-ACP paste. During the 14-day bleaching regimen, the samples will be stored in artificial saliva. The Vickers microhardness will be assessed at baseline (T0) and immediately after the bleaching regimen (T14) using a microhardness tester. Scanning electron microscopy will be used to study the morphology of enamel with and without CPP-ACP. Results There was a significant increase in microhardness of enamel in group used CPP-ACP with carbamide peroxide (10 % and 15 %) and surface morphology was improved by using the remineralizing agents. Data will be analyzed statistically using ANOVA and Post hoc test. Conclusions The use of CPP-ACP paste with 10 % and 15 % carbamide peroxide increased post bleaching enamel microhardness and was effective on repairing enamel surface morphology.