Objective: The purpose of this clinical trial was to evaluate the efficacy of 2 over-the-counter whitening systems: a liquid whitening gel (5.9% hydrogen peroxide, twice a day for 15 minutes), and a sodium chlorite-based whitening gel applied in a tray system (10 minutes twice a day). Method and Materials: Sixty volunteers (minimum shade A3 on 1 maxillary tooth) were selected to participate in this single-blind (examiner-blinded), single-center, 2-group trial. The subjects were randomly divided into 2 groups (n = 30 each) and instructed to bleach their teeth for 2 weeks. Efficacy was measured using the Vita Classical shade guide and a spectrophotometer at baseline, as well as after 2 weeks and 6 months. Results: For the subjectively measured tooth shades, improvement for maxillary canines was 2.03 ± 3.67 tooth shades in group 1 and 1.08 ± 2.19 tooth shades in group 2 after 2 weeks; the maxillary incisors revealed a tooth shade improvement of 0.83 ± 1.71 tabs in group 1 and 0.73 ± 2.22 tabs in group 2 (P .05, except maxillary incisors in group 2; t test). Objectively measured tooth shade scores revealed a change of 0 ± 0.25 tooth shade tabs (P > .05). Conclusions: The bleaching gel containing hydrogen peroxide achieved a slight improvement, and the sodium chlorite-based bleaching gel achieved only a small tooth color improvement. Moreover, subjectively and objectively measured tooth shades revealed considerably different results in the clinical situation. Keywords: home tooth bleaching, hydrogen peroxide, over-the-counter bleaching products, randomized clinical trial, sodium chlorite