Objective: The purpose of this study is to assess the sleep behaviors, sleep problems and frequency, and relationship with psychiatric comorbidities in ADHD Combined type and to evaluate the effect of sleep problems on quality of life. Method: Forty-six boys, aged 7 to 13 years, with ADHD-combined type and 31 healthy boys were included. ADHD children were never treated for sleep or psychiatric disorders. Intelligence quotient (IQ) test scores were minimum 80, body mass index were normal and did not have medical disorders. Parents completed Children’s Sleep Habits Questionnaire, Conners’ Parent Rating Scale and The Pediatric Quality of Life Inventory (PedsQL) and participants were asked about sleep behaviors and were administered PedsQL and Schedule for Affective Disorders and Schizophrenia. Results: The frequency of sleep problems in ADHD is 84.8%, higher than the control group (p = .002). Evaluating PedsQL scores, the quality of life is worse in physical, psychosocial health, and total life quality (p < .05). ADHD group with sleep problems have more night wakings than control group with sleep problems (p = .02). The comorbidity do not increase sleep problems. The frequency of parasomnias is increased in group with learning disorders (p = .05). Conclusion: The results of this study, which controls for a number of possible confounders found in previous examinations of ADHD and sleep, support the results of a number of other studies that have found an increased overall prevalence of parent-reported sleep disturbances in children with ADHD compared with healthy control participants. As the ADHD group have more night wakings than the control group through the night, it is thought that night wakings that cause a partitioned sleep may be important signs seen in ADHD. That could be suggested by two hypotheses. First one is that, daytime sleepiness is more common in ADHD and those children present excessive hyperactivity during the day to stay awake and the second one is the improvement of ADHD signs when the drugs for sleepiness are used. Usage of standardized and valid diagnostic criteria, exclusion of adolescence, gender, socioeconomic level, primary sleep problems, medical disorders and low IQ level, making allowances for effect of comorbidities and having compared with the control group are the important methodological features of this study. The most important limitation of this study is small sample size that makes the findings less generalizable to other groups of children with ADHD, and another one is not having used objective measurements together with subjective measurements. In conclusion, these results underscore the importance of screening all children who have a symptom constellation suggestive of ADHD for sleep problems that may either play a causative role or exacerbate the clinical appearance of ADHD in a given child. Correct evaluation and treatment of sleep problems increase the life quality of family and child and also decrease the severity of ADHD symptoms. (J. of Att. Dis. 2013; XX(X) 1-XX)