SUMMARY
One of the main features of the research system is scientific participation, which is growing rapidly. Scientific participation is often considered as an effective solution for countries to acquire scientific and technological knowledge. Therefore, the purpose of this study was to determine the average number of authors of articles based on the journal indexes, type of articles, and the authors’ gender in Iranian Medical Journals with different indexes in the period 2015-2020. In this cross-sectional study, 60 articles in randomly-selected Iranian Journal of Medical Sciences were selected by simple sampling. After categorizing the journals according to their indexes, we selected 10 journal titles from each index and 20 titles of the first published article of each journal were selected according to the type of article. Then, the data were entered into Excel and analyzed by using SPSS software version 21. The total number of authors of articles according to their index was 4.24. Also, the findings showed that there was a significant difference in the mean of the number of authors in Iranian medical journals. (P-value =0.000). It is suggested that the authors of journal articles should be more inclined to write articles in groups in order to increase scientific cooperation between Iranian authors of medical science journals. This can play an important role in raising the quality of articles.