The aim of this study was to investigate the color of the natural maxillary incisor tooth from Japanese people of all age groups. These results were compared with the Trubyte Bioblend shade guide. The subjects of this study were in the age range of 13-84, 42 male and 45 female making 87 people in total. Areas with 1.0-mm diameter at five sites were measured along the tooth axis for L*,a*,b*, according to CIELAB color spaces using a Spectroradiometric Color Computer. At the incisal site, two significant positive correlations were found between age and a* (r = 0.376, p < 0.001), and b*(r = 0.483, p < 0.001). At the center site, a significant negative correlation (r = -0.418, p < 0.001) was found between age and L*, but positive correlation (r = 0.497 p < 0.001) was found between age and b*. At the cervical site, a significant negative correlation (r = -0.326, p < 0.01) was found between age and L*, but positive correlation (r = 0.702, p < 0.001) was found between age and b*. Near the root, particularly, the values of a* were greater than those suggested by the Trubyte Bioblend shade guide. In conclusion, as the Trubyte Bioblend shade guide does not match the natural tooth color in red-green chromaticity near the root it is significant for us in dentistry to develop new shade guides that match the Japanese people based on the data collected. (C) 2000 John Whey & Sons, Inc.