This study measured the goniochromatic properties of human tooth dentin through the viewing angle dependent color change measurement, and determined the influence of the microscopic structural nonuniformity of dentin surface on the gonioappearance. Color of 21 polished dentin specimens was measured by a spectroradiometer in wet and dry conditions. Spectral reflectance values were obtained with 0, 20, 45, and 70 degrees aspecular viewing angles to the surface. These values were converted to CIE color coordinates (CIE L*, a*, and b*) relative to the specular set (0 degrees) standard white tile to determine general goniochromatic effect, and to the same aspecular set standard white tiles to determine the influence of nonuniformity on dentin surface caused by dentinal tubules. Color coordinates and chroma were influenced by the viewing angle (P < 0.05). As to the influence of nonuniformity, CIE L* and a* and chroma were influenced by the viewing angle while CIE b* was not (P = 0.05). Goniochromatic effect of human dentin was confirmed instrumentally, and the nonuniformity of dentin increased goniochromatic effect. Based on these results, goniochromatic properties of intact teeth should be studied further, and restorative materials that can simulate these properties should be developed. (c) 2011 Wiley Periodicals, Inc. Col Res Appl, 37, 206-211, 2012; Published online 1 March 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/col.20663