Background: Denture hygiene is an important factor to remove dental plaque and discoloration, to provide optimal oral health, and to prevent denture stomatitis. Aim: The purpose of this study was to evaluate the effect of coffee staining and denture cleaner on the color stability of two differently polymerized (heat and microwave) denture acrylic resin in vitro. Materials and Methods: Two commonly used denture base acrylic resins and effervesecnt tablet form denture cleaner were used in this study. Disc-shaped specimens from each acrylic resin were polymerized according to the manufacturer's instructions (n = 7). Color values were recorded before and after immersion in distilled water (I), denture cleaner (II), coffee (III), and coffee + denture cleaner (IV) with a tristimulus colorimeter using CIEDE2000 color difference formula. Two-way analysis of variance (ANOVA) and Fisher's least significant difference tests were used for multiple comparisons at a 95% confidence level (P < 0.05). Surface topography of the acrylic resin denture base specimens before and after immersion were taken under 500 x magnification. Results: The two-way ANOVA revealed significant interactions between denture base resins and solutions (P < 0.001). Immersion in denture cleaner and coffee solution caused significant color changes in acrylic resin denture bases. Conclusion: Heat- and microwave-polymerized acrylic denture base resins can show different color stability. Immersion in coffee and denture cleaner solutions can cause noticeable color changes.