Background and purpose: The latest 2022 edition of the International Classification of Diseases (ICD-11) includes updated descriptions and diagnostic rules for "depressive episodes" and " generalised anxiety disorder". The only self- assessment that is consistent with these disorders is the International Depression Questionnaire (IDQ) and the International Anxiety Questionnaire (IAQ). The aim of the present study was therefore to investigate the psychometric properties of the IDQ and the IAQ in Iran, focusing on the student population.

Materials and methods: In the form of a descriptive study, 550 students of medical sciences universities in Tehran who were studying in 2023 were selected by convenience sampling and answered the research questions. To evaluate the reliability of these two questionnaires, two methods of internal consistency and test-retest were applied with an interval of two weeks. Their construct validity was assessed in the student sample using exploratory and confirmatory factor analysis.

Results: According to the results, the Cronbach's alpha coefficient for the depression and anxiety questionnaires was 0.92 and 0.93 respectively and the intraclass correlation coefficient was 0.86 and 0.84respectively, which indicates a high internal consistency and retest reliability of the two questionnaires. The confirmatory factor analysis showed that all questions in both questionnaires are related to one factor.

Conclusion: In general, it can be concluded that both questionnaires can be used as a brief measure in clinical and research settings for screening, diagnosingand monitoring the treatment of depression and anxiety in the student population.