The DSM-IV-TR (Diagnostic and Statistical Manual of Mental Disorders, 1994, American Psychiatric Association) describes attention deficit hyperactivity disorder (ADHD) as a heterogeneous disorder; providing diagnostic criteria for three subtypes: hyperactive/impulsive (ADHD/HI), inattentive (ADHD/I), and combined type (ADHD/C). Differences among the subtypes are well defined, but there may be also differences in terms of treatment responses. The aim of this study is to assess the responses of ADHD/I and ADHD/C to atomoxetine treatment. The medical records of the January-June 2012 term, first time referrals to outpatient clinic, were reviewed, and 37 ADHD diagnosed primary school age children (18 ADHD/I, 19 ADHD/C) that were treated with atomoxetine were determined. Thirty-five of them who completed 8 weeks of treatment duration were recruited for the study. The children with an ADHD medication use history in 2 months time prior to onset of treatment and/or the children receiving additional psychopharmacologic treatment to atomoxetine were excluded. Baseline and eighth week assessment, records were evaluated. Efficacy assessments included Turgay DSM-IV ADHD Screening and Rating Scale parent and teacher forms (T-DSM-IV) and Clinical Global Impression Scale-Severity and Improvement subscales. Safety assessments included laboratory and body weight assessments, ECG, heart rate, and blood pressure evaluations (baseline and eighth week) along a scale filled by the parents at the eighth week to review side effects. Atomoxetine was found to be effective in both ADHD/I and ADHD/C groups. Atomoxetine also decreased the opposition defiance subscale scores of T-DSM-IV (both parent and teacher forms), whereas it was not found to make statistically significant difference in the conduct disorder subscale scores. Mean difference in 8-week time in T-DSM-IV hyperactivity subscale and total scores of parent and teacher forms; inattention subscale scores of only parent forms and the CGI- severity subscale scores; differed significantly among the ADHD/I and ADHD/C groups; that ADHD/C types responded better to medication. Results of this study revealed that atomoxetine is effective both in ADHD/I and ADHD/C subtypes. ADHD/C types may be responding better to atomoxetine treatment than the ADHD/I subtypes.