Abstract Background and Objectives: Attention-deficit/hyperactivity disorder (ADHD) often persists into adulthood. Instruments for diagnosing ADHD in childhood are well validated and reliable, but diagnosis of ADHD in adults remains problematic. Attempts have been made to develop criteria specific for adult ADHD, resulting in the development of self-report and observer-rated questionnaires. To date, the Conner’s Adult ADHD Rating Scales (CAARS) are the international standard for questionnaire assessment of ADHD. Methods: The current study evaluates a Persian version of the CAARS self-report (CAARS-S-SV). Method of study is analytic-descriptive, from type of studies correlation-psychometric. In order to study the psychometric properties of the questionnaire in normal population, 1021 subject were recruited to fill out the CAARS-S-SV. To determine internal consistency and test consistency, Cronbach's alpha and the correlation between test-retest and test were used. An exploratory and confirmatory factor analysis was performed to examine the Farsi factor structure and confirm the structure of the original American version. Also, in order to determinate the Criterion validity or diagnostic validity, the sample consisted of 74 adult with ADHD and 75 controls. A case-control study was carried out (adult ADHD vs. non-ADHD). The diagnosis of ADHD was evaluated with the Structured Clinical Interview for DSM-IV (SCID-I).   Results: Factor analysis was done with a Principle axis factoring analysis followed by an Oblimin rotation. The Kaiser-Meyer-Olkin measure of sampling adequacy tests was .912 (remarkable) and the Bartlett’s test of sphericity was 3 (435) = 2011.36, P < .0001, indicating the appropriateness of the factor analysis. This three-factor model accounted for 68% of the explained variance. The Cronbach's alpha coefficient of the three factors was 0.802, 0.758 and 0.869 respectively. The Persion version of the CAARS–S: SV is a valid and reliable scale to discriminate between ADHD adults and controls. A confirmative analysis that was based on the 30 items of the original American model showed a high model-fit. Also, the results confirm the internal consistency and stability of the test. Discussion and Conclusions: The confirmative factor analysis results in such a high model-fit that use of the American version is justified with respect to international multicenter studies, for which this instrument will be highly valuable.