Aim: to evaluate the changes of surface hardness and remineralizing effect of nano-carbonate apatite on demineralized stripped enamel surfaces by SEM and micro-hardness examination. Materials and Methods: Forty-five extracted premolars received proximal stripping using diamond coated metal hand-held strip. Each tooth was sectioned by means of a low-speed air and watercooled diamond disc along its major axis into mesial and distal halves i.e. obtaining 90 tooth sections (30 unstripped &60 stripped) and divided into 3 groups: Group A (A1 15 unstripped; A2 15 stripped) served as control. Group B (B1 15 unstripped; B2 15 stripped) specimens were placed in lactic acid for 1h three times a day with 2h preservation in artificial saliva in between for 7 days. Group C (C1 15 unstripped; C215 stripped) specimens were received same treatment as group B then treated with remineralizing agent (APF for C1& n-CAP for C2) immediately after each demineralizing bath. Results: SEM results showed greater demineralization in subgroup B2 compared to B1, while it revealed greater remineralization in subgroup C2 (n-CAP) compared to C1 (APF). Surface microhardness examination results using Mann-Whitney test showed significant decrease in SMH of group B2 compared with (A). SubgroupC1 (APF) showed increase in SMH compared with subgroup B2 with no significant, and decrease compared with group (A). While there was no significant in SMH of subgroup C2 when compared with group (A), however there was highly significant increase in SMH of subgroup (C2) compared with those of subgroup B2 followed by subgroup C1. Conclusion: N-CAP could be considered as a valuable non-fluoride alternative to fluoride containing formulations used for suppressing demineralization and enhancing remineralization of enamel. It can be considered as a potential caries preventive agent showing promise for the recovery of damaged enamel structures