Objective: The purpose of this study was to investigate the effect of sensory modulation and sleeping among 30 adolescents diagnosed with ADHD, compared with 28 adolescents without ADHD. Method: Two questionnaires were completed by parents to assess the participants’ level of ADHD symptoms. Two other questionnaires were completed by the participants assessing difficulties in sensory modulation and sleep. Results: The ADHD group had more sensory difficulties in Activity Level, Hearing, and Low Registration, and more difficulties in the Sleep Behavior variables. Higher correlations between the sensory variables and the sleep measures were found in the ADHD group as compared with the non-ADHD group. Significant differences between correlations were found between three sleep measures and four sensory variables. Conclusion: The discussion is devoted to an assessment of the relationships between the measures, with the conclusion that among adolescents with ADHD, it is important to assess and treat possible sensory and sleep difficulties. (J. of Att. Dis. 2012; XX(X) 1-XX)