Background: Submitting thesis is one of the most important tasks of medical students Moreover medical theses can be considered as a basic source for improving the health statues of the society Objective: The aim of this study was critical appraisal of the submitted theses by medical students of Rafsanjan Medical School during 1993 2003 Methods : In the present cross sectional study 332 Medical theses were evaluated by using a questionnaire Data analysis was done by using simple descriptive methods and Chi square test Results: According to the results 258 theses (777%) have been well written Theses submitted during the recent years had better quality comparing to others (924% versus 739%) Theses supervised by more than one leader were better in comparison to those with only one leader (915% versus 739% P= 0002) Moreover theses with at least one advisor had a better quality than those conducted without any advisor (884% versus 397% P= 00001) Conclusion : Better quality of theses submitted during the recent years can show the beneficial effect of participation of both medical students and their supervisors in Research Methodology Workshops held in the recent years This fact has also been reported in other studies