Objective <p>This study aimed to analyze the impact of various beverages on the color change, surface roughness, and bacterial adhesion of nanohybrid and microhybrid composites.</p> Materials and methods <p>Four resin composites with different filler characteristics were evaluated: two microhybrid composites (Dr. Müller Rhein [DRM] and Herculite Classic [HCM]) and two nanohybrid composites (Dr. Müller Kaiser [DRN] and Clearfil Majesty Esthetics [CME]). Each resin composite group was divided into four subgroups (<i>n</i> = 12) for immersion in beverages (control: distilled water; coffee, cola, and red wine). Initial color and surface roughness were measured, and measurements were repeated after 12 days of immersion. Saliva was applied to the sterilized sample surfaces to stimulate pellicle formation, and the samples were incubated. To evaluate bacterial adhesion, colony counts of <i>Streptococcus mutans</i> (ATCC 25175) were reported as CFU/ml. Additionally, one sample from each subgroup was cultured for scanning electron microscopy. Two-way analysis of variance was used to compare variables with normal distributions across resin composites and beverages; pairwise comparisons were performed using the Tukey test. Two-way robust ANOVA was used for variables that were not normally distributed, and pairwise comparisons were performed using the robust t-test with Holm’s correction. Results for quantitative variables are presented as mean ± standard deviation and median (minimum: maximum). The significance level was set at <i>p</i> &lt; 0.05.</p> Results <p>Dr. Müller Kaiser and Clearfil Majesty Esthetics were the most resistant to discoloration (<i>p</i> &lt; 0.05). The highest surface roughness and bacterial adhesion were observed in the microhybrid composites Dr. Müller Rhein and Herculite Classic, while the lowest bacterial adhesion was observed in the nanohybrid composites (<i>p</i> &lt; 0.05). Red wine and coffee exhibited the highest discoloration values, with no statistically significant difference between them (<i>p</i> &gt; 0.05), whereas cola showed the greatest effect on surface roughness.</p> Conclusions <p>Exposure of resin composites to various beverages can negatively affect surface properties, color stability, and promote biofilm formation. These findings provide preliminary insight into the effects of commonly consumed beverages on resin composites under controlled laboratory conditions. However, further in vivo and clinically simulated studies are required before definitive clinical recommendations can be made.</p> Clinical significance <p>Considering patients’ dietary habits during material selection may improve long-term esthetic and biological outcomes.</p>