<p>To evaluate the effect of an acidic beverage and simulated gastric acid on the color stability, gloss and surface roughness of different monolithic CAD/CAM materials. Feldspathic ceramic (FC-CEREC Blocks), Lithium disilicate ceramic (LDC-UP-CAD), and resin nano-ceramic (RNC-Lava Ultimate) specimens were subjected to 3 different polishing methods (mechanical-M, glaze-G, and mechanical + glaze-MG) (<i>n</i> = 10). After baseline measurements of color, gloss, and surface roughness, three different immersion protocols (artificial saliva, acidic beverage, and simulated gastric acid) were applied, followed by repeated measurements. Color change was calculated by using the ∆E00 formula. The changes in gloss (ΔGU) and surface roughness (ΔRa) were calculated by subtracting the after-immersion values from the baseline measurements. Statistical analysis was performed using analysis of variance, Kruskal-Wallis and, post-hoc Bonferroni tests (α = 0.05). Statistically significant differences were found for ∆E00 and ΔGU values (<i>p</i> &lt; 0.05), whereas differences in ΔRa measurements were insignificant (<i>p</i> &gt; 0.05). The color change in the acidic beverage was higher for mechanically polished RNC, irrespective of the polishing method (<i>p</i> = 0.025) and immersion solution (<i>p</i> = 0.002). The color change in the simulated gastric acid was higher for mechanically polished LDC compared to other polishing methods (<i>p</i> = 0.003). All groups showed higher ΔGU values when subjected to gastric acid than artificial saliva irrespective of the polishing methods (<i>p</i> &lt; 0.05). Glaze application is necessary to maintain the color of monolithic CAD/CAM restorations for patients who consume acidic beverages frequently. Clinicians should be cautious about gloss changes in monolithic restorations for bulimia nervosa patients.</p>