Objectives: It seems that internet occupy large part of youth's life. Each year more reports are published in the field of internet addiction disorder (IAD). In DSM-IV-TR, internet addiction disorder is classified under impulse control disorder not elsewhere classified. This study evaluates questionnaire correspond-dence diagnostic criteria of DSM-IV-TR for diagnosis of IAD.
Method: In this cross-sectional research 400 Isfahan University students were selected through quota sampling method The subjects completed a demographic questionnaire, CIUS and YDQ. Clinical interview (based on DSM-IV-TR) was performed for all of the subjects. For data analysis we have used face, discriminative and concurrent validity, inter-scorer reliability (Kappa coefficient), split half, test-retest and ROC Curve using SPSS software. Results: Concurrent validity was(r=0.78, 0/81), discriminative validity was (r=0/62) YDQ has a internal consistency (Kappa=0.80) and split-half validity (r=0/64), test –retest reliability (r=0.74,p<0.01). Conclusion: Iranian version of Diagnostic Questionnaire was valid and reliable. Considering with lack of valid and reliable questionnaire to measure addiction to the Internet, using the YDQ is considered a suitable tool for measuring Internet addiction in future research.