Objectives: The aim of this research was to investigate the quality of studies on the prevalence of psychiatric disorders in Iran. Method: All studies on the prevalence of psychiatric disorders among Iraniangeneral population as well as school children over 15 were identified through searching several databases including PubMed, ISI WOS, PsychINFO, CINAHL, Irandoc, EMBASE, IranPsych, IranMedex, and Scientific Information Database as well as reference lists of the accessed documents, unpublished reports, conference proceedings and dissertations. The original studies, which contained an estimation of the prevalence of “any psychiatric disorder” (overall prevalence) among a sample of general population or high school students in the country were selected. A quality assessment  checklist was developed based on the following criteria: accurate description of research questions, random sampling, representativeness of the study sample for a defined target population, using the same method of data collection for the entire sample, using valid and reliable tools, and proper analysis of the results. Results: The assessment was performed on those studies on the prevalence of any psychiatric disorder in the country that had used random sampling (43 studies). It showed that in only about 40% of the studies the sample was representative of the target population. In more than 25% of the studies, validity and reliability of the Persian translation of the instruments were not assessed or were not reported. In total, nearly a third of studies had acceptable quality (random sampling, application of valid and reliable tools, and sample representing the target population). Conclusion: Although this research - as part of a systematic review-was based only on a group of prevalence studies in psychiatric disorders, its findings indicated that a significant proportion of these studies are non-compliant with key quality measures. Instead of mere emphasis on increasing the number and quantity of studies, policy makers should employ strategies to improve research quality.