The aim of this study was to obtain information about tooth color changes in 25 extracted human incisors resulting from repeated bleaching with a 10 percent carbamide peroxide gel. Using a colorimeter, the author recorded color changes in the L*a*b* color space after each bleaching period. The observed tooth color change was found to be dependent on the bleaching time, the specific bleached section and the initial color. The most significant total tooth color change was observed in the incisal section of the crown, followed by the middle and the cervical sections.