Objective The study aims to compare in vitro stain resistance, color stability, gloss, and gloss retention of a nano-filled resin-modified glass ionomers (RMGIs) to a traditional RMGI and resin-based composites (RBCs). Materials and Methods Specimens (N=20) were fabricated from a nano-filled RBC (Filtek Supreme Plus, 3M ESPE, St. Paul, MN, USA), a nanohybrid RBC (Clearfil Majesty Esthetic, Kuraray; Tokyo, Japan), a nano-filled RMGI (Ketac Nano, 3M ESPE), and traditional RMGI (Fuji II LC, GC America, Chicago, IL, USA). L∗a∗b∗ values were recorded with a spectrophotometer, and gloss was measured with a glossmeter. For each material, 10 specimens were stored in distilled water in darkness for 1 week and 10 specimens were placed in a staining solution for 1 week. After storage, specimens were cleaned and L∗a∗b∗ and gloss measurements were remeasured. Results Data were analyzed by analysis of variance (ANOVA) and Tukey analyses. Regarding color change, materials ranked: Ketac=Fuji>Filtek>Clearfil in water, and Ketac>Fuji>Filtek>Clearfil in staining solution. Prior to storage, the initil gloss of the materials ranked: Filtek≥Clearfil≥Ketac>Fuji. After storage, the materials ranked: Filtek=Clearfil>Ketac>Fuji in water, and Filtek>Clearfil>Ketac>Fuji in staining solution. Gloss retention was similar for all materials in water and gloss retention ranked: Filtek=Clearfil>Ketac=Fuji in staining solution. Conclusions The nano-RMGI showed less stain resistance but higher gloss than the traditional RMGI. Both RMGIs had more color change, less stain resistance, lower gloss and less gloss retention than the RBCs. Clinical Significance The clinician should be aware that the use of a nano-RMGI may improve the gloss of an RMGI restoration; however, color change will likely occur, particularly if the patient consumes a staining diet.