The aim of this study was to determine the agreement between the two systems in opioid users in the general population and a clinical sample. Two series of data were used in this study. The first was the data of 236 home-residing opioid abusers aged 15-64, who had previously participated in the Iran Mental Health Survey (IranMHS) in 2011, and the second was the data of 104 general psychiatry patients from inpatient or outpatient wards of two psychiatry hospitals in Tehran. Opioid use disorders were evaluated with CIDI-version 2.1. The disorders were assessed in all participants who used opioid substances for at least 5 times during the past 12months. In the sample from the general population, the agreement between the two systems on the diagnosis of dependence was excellent (0.81). The agreement between the two systems on the diagnosis of abuse and harmful use was 0.41. In the clinical sample, the agreement between the two systems on the diagnosis of dependence or any opioid use disorder was 0.96 and 0.93, respectively. The agreement between abuse and harmful use was 0.9 and -0.02 with and without regarding hierarchy, respectively. The inter-rater reliability of both DSM-IV and ICD-10 systems for all diagnosis was more than 0.95. The results of the diagnosis of dependence in the two systems had a weak concordance with treatment. The diagnostic criteria of DSM-IV and ICD-10 regarding dependence are very similar and the diagnosis produced by each system is concordant with the other system. However, the two systems have noticeable discrepancies in the diagnosis of abuse and harmful use. The discrepancies result from their conceptual differences and necessitate further revision in the definition of these disorders in the two systems.