Objective: Although there are several clinical studies on in office vital bleaching in adults, there are no Randomized Clinical Trials for the efficacy of this application in adolescents. The aim the study was to evaluate the efficiency of two bleaching systems on adolescents for twelve-months follow-up. Study design: Twenty-eight volunteers, aged between 13-18, randomly divided into two groups. Two commercial in office bleaching systems were used: G1 (n=14): Zoom2 25 % HP with UV light and G2 (n=14): Beaming White 36% HP with LED light in a single 3x15minute procedure. The color assessment was made with a spectrophometer; before and after bleaching; 48 hours; 1, 6 and 12 months later. Color enhancement and maintenance of two techniques over 12 months were compared by two ways ANOVA and Student's t test. Sensitivity was evaluated on a scale with Wilcoxon test. Results: Both groups demonstrated similar and significant tooth color enhancement and did not reveal any statistically significant differences between them. However, a relapse of the tooth shade was observed with the low concentration agent/ultraviolet light system. No sensitivity was observed in any patients. Conclusion: Two in-office bleaching systems can be used successfully on young permanent teeth. For long-term successful results, high concentration/LED light may be more effective.