Purpose : The aim of this in vitro study was to evaluate the effect of different oral media (acid media, topical fluoride and mouth wash) on the surface roughness and color stability of two milled esthetic materials (composite resin materials and feldspathic ceramic materials). Material and methods: In this study a total of thirty disc samples were machine milled by the aid of CAD/CAM system. The samples were divided according to the material of construction into two main groups. Each group was composed of 15 samples (milled composite resin blocks and milled feldspathic porcelain blocks). All sample groups were then immersed in 20ml of artificial saliva for 24 hours to be baseline assessment. Each group was further subdivided into three subgroups each of five samples according to the type of immersion media. The samples of subgroup (1) were immersed in the acid media for 12 days. For subgroup (2) the samples were immersed in topical fluoride agent for 6 hours. While for subgroup (3) the samples were immersed in the mouth wash for 12 hours. All immersion times were equivalent to consumption of the materials of immersion media for one year by the patient. For quantitative evaluation of surface roughness, all samples were subjected to profilemetric measurements. While fore qualitative assessment of the surface topography SEM evaluation was carried out for selected samples from the different groups and subgroups. Color measurement tests were also conducted for all the samples by spectrophotometer.These measurements were made twice, once after artificial saliva immersion and again after storage in different immersion media for the specific time. Results : There was no statistically significant difference between Composite resin samples that immersed in acid media or topical fluoride, and ceramic samples that immersed in acid media or topical fluoride; all showed the statistically significantly highest mean Ra values. Composite samples that immersed in mouth wash showed statistically significant higher Ra value compared to the ceramic samples that immersed in the mouth wash which showed statistically significant lower Ra value. Spectrophotometer measurements of all the groups and subgroups revealed statically significant higher mean ΔE values for ceramic groups than the composite resin groups. All changes in the color were clinically acceptable except for ceramic samples that immersed in acid media. Conclusion: Milled composite resin materials provided comparable results to milled feldspathic ceramics with regard to roughness and color change after immersion in media with different pH.