Aim : the present study was carried out to compare between non-invasive treatment modalities using (fluoride varnish (FV) and Nano-HAP based reminerlizing agents) and minimal-invasive treatment modalities using (resin infiltrant materials) on surface micro-hardness, surface topography and colour stability of WSLs.MethodsA total 80 sound human permanent premolars were used in this study.The specimens were divided into four equal groups 20 teeth for each group. According to treatment modality group A0: resin infiltration material, group A1 nano hydroxyapatite based remineralizing agent, group A2 fluoride varnish and group (A2) artificial saliva as control group.The surface microhardness (SMH) of each specimen was assessed using Vickers microhardness tester. Scanning electron microscope were used to assess surface morphological characters of enamel surface at different stage. Color stability of enamel surface at different stage were assessed by spectrophotometer. Results. both resin infiltration material and Nano hydroxyapatite based remineralizing agents showed the highest statistically significant mean surface microhardness values and highest statistically significant mean of color stability Conclusion:Nano hydroxyapatite based remineralizing agent and resin infiltration system are the most effective treatment modalities for incipient carious enamel lesions.