SUMMARY Objective: To perform a systematic review to answer the following research question: Is at-home bleaching in adults with more concentrated carbamide peroxide (CP) gels as effective and safe as bleaching performed with 10% carbamide peroxide gels? Methods and Materials: A comprehensive search was carried out in the MEDLINE via PubMed, Scopus, Web of Science, LILACS, BBO, Cochrane Library and SIGLE, without restrictions. IADR abstracts (1990 to 2016) and unpublished and ongoing trial registries, dissertations and theses (ProQuest Dissertations and Periodicos Capes Theses Databases) were also searched. The risk of bias of the included studies was analyzed using the Cochrane Risk of Bias tool from the Cochrane Collaboration. We meta-analyzed the data using the random effects model to compare 10% CP and more concentrated CP gels in terms of color change (ΔSGU or ΔE) and risk and intensity of tooth sensitivity (TS). The quality of the evidence was rated using the GRADE approach. Results: After the database screening, 182 articles remained, and this number was reduced to 17 after examination of the abstracts and/or full texts. Four articles were follow-ups of earlier studies, and thus we collected 13 studies. Ten studies were at unclear risk of bias, while three were at low risk of bias. Lower risk and intensity of TS was observed for 10% CP. The odds ratio for the risk of TS was 0.41 (95% CI 0.20 to 0.84, p =0.01), and the difference in means for TS intensity was 0.44 (95% CI 0.67 to −0.20, p =0.0003). No significant difference was observed in terms of color change in ΔSGU (difference in means 0.29; 95% CI 0.25 to 0.83, p =0.29) and for ΔE (difference in means −0.16; 95% CI 0.38 to 0.06, p =0.16). Except from the ΔSGU, for which the evidence was graded as low quality, the other outcomes were considered at moderate quality. Conclusions: At-home bleaching with 10% CP showed similar bleaching efficacy with lower risk and intensity of TS in comparison with more concentrated carbamide peroxide gels.