The purpose of this study was to evaluate the efficacy of two different 10% carbamide peroxide bleaching products just after treatment and after a 6-month follow-up period. Methods. Two 10% carbamide peroxide products (Opalescence PF and Nite White ACP) were applied nightly for 14 days, according to the manufacturers' instructions. The color of teeth 11 and 21 of thirty-four subjects having A2 or darker teeth were measured with a spectrophotometer (L(∗); a(∗); b(∗)) before treatment, just after treatment (14 days) and after 6 months. Results and Conclusions. Both products produced significant whitening of teeth with total color change (ΔE(ab) (∗)) of approximately 5.20 units. There was a significant improvement in all 3 color coordinates (L*, a*, and b(∗)) for up to 6 months postbleaching (P < .05). Nite White showed a higher degree of relapse (27%) than Opalescence (18%) over the 6-month period. It is suggested that rebleaching after 6 months is not necessary.