Objective: The aim of this study was to evaluate color compatibility of corresponding resin composite shades keyed to Vitapan Classical shade guide (Vita). Method and Materials: Twenty-one shades of 6 commercial resin composites were analyzed. Specimens (n = 5) were made as disks, 11 mm in diameter and 2 mm thick, using cylindrical molds. Specimens were polymerized according to manufacturers' suggestions using a light-curing unit. Data were collected using a spectrophotometer and analyzed using the appropriate color difference metric equations. A total color difference (DE*ab) greater than or equal to 3.7 was considered a mismatch. Analysis of variance and Fisher's probable least-squares difference (PLSD) test. intervals for comparison of means were calculated at the .05 level of significance. Results: Mean DE*ab values among A2, B2, C2, and opaque A2 shade pairs were 4.4 (1.8), 7.3 (3.2), 5.6 (2.8), and 6.5 (1.8), respectively, while the mean color difference for all the pairs compared was 5.8 (2.8). For A2 shades, DL*, Da*ab, and Db*ab values ranged by 5.3, 2.3, and 6.7, respectively. Corresponding values for B2 shades ranged by 10.5, 2.2, and 11.5; 7.9, 2.2, and 4.3 for C2 shades; and 7.9, 1.4, and 4.4 for opaque A2 shades. Fisher's PLSD critical intervals for comparing DE*ab values among the shades and composite pairs were 0.07 and 0.15, respectively (P .0001, power 1.00). Conclusion: Overall, poor color compatibility of shade pairs of identical shade designation was recorded. The best color match was recorded for A2 shade pairs, followed by C2, B2, and opaque A2 shade pairs. Keywords: color, color measurement, dental materials, optical properties, resin composite, standardization, shade