This research was designed to evaluate the effect of pretreatment by either acid etching or micro abrasion on the remineralizing potential of three different calcium phosphate based remineralizing agents using surface microhardnesss test. Materials & Methods: A total of 150 sound human mandibular molars were used in this study. Artificial enamel carious lesions were induced by immersing the specimens in a demineralizing solution for 4 days. The enamel specimens were divided randomly into three groups, according to the surface pretreatment modality, n=50. Group A1: no pretreatment (Control), Group A2: Acid etching using 35% Phosphoric acid and Group A3: micro-abrasion using microabrasion paste. Then they were all subdivided into five sub groups, n=10, according to the remineralizing agent used; Sub-group B1: molars stored in artificial saliva, Sub-group B2: fluoride varnish, Sub-group B3: CPP-ACP varnish, Sub-group B4: f-TCP varnish and finally Sub-group B5: Novamin paste. All products were applied according to the manufacturer’s instructions, and specimens were finally subjected to a pH cycling protocol of alternating demineralization (2 hours) and remineralization (22 hours) for eight consecutive days. The surface microhardness (SMH) was assessed using Vickers microhardness tester, prior to demineralization of the specimens as a baseline (SMH/Baseline), following demineralization (SMH/Demineralization) and finally, after the remineralization regimens & pH cycling (SMH/Remineralization), then mean surface microhardness recovery percentage was calculated SMHR %. Results: showed that using microabrasion as a pretreatment enhanced the efficacy of all remineralizing agents. Unlike, acid etching which showed no significant difference in comparison to the no pretreatment group. Regarding the remineralizing agents employed, the following results were revealed, the highest SMHR% was found in Novamin (70.19 ± 8.09) followed by TCP (59.38 ± 9.36), CPP- ACP (55.21 ± 2.58) and Fluoride (51.12 ± 2.48). While the lowest SMHR% was found in Saliva group (19.16 ± 3.73) regardless of the surface pretreatment applied. Conclusion: Microabrasion followed by a remineralizing agent is a successful minimally invasive technique and may be considered as an alternative to the restorative approach in early carious lesion.