Background & Objective: Writing dissertation is an opportunity for students to become familiar with methodology of a research process during the period of education In recent years there has been special emphasis on proper studies structure similar and scientific writing process in research reports and dissertations Attending methodology workshop for faculties and students together with preparing booklets has helped a lot but still there is a long way to meet the optimal standards This study was conducted to evaluate methodological structure of medical dissertations in Golestan University of Medical Sciences from 1996 to 2005 Methods : This is a descriptiveanalytic Study For data collection all of the dissertations (257) were studied and scored with a check list that was designed for a national research on thesis The maximum score for each thesis was 500 Results : The results showed that the mean score ( ± SD) of the dissertations has increased from 2699( ± 78) in 1996 to 3515( ± 331) in 2005 According to this study 769 percent of dissertations had statistical consultants and the most frequent design was crosssectional There was a significant relationship between final score of dissertations and grade of them (r=038 P=0039) The weakest parts of the dissertations were methodology then statement of problem and then discussion Conclusion : Although methodology structure of medical dissertations has improved considerably recently but there is a long way to reach optimal status Education of faculty members and students in research field guiding students for finding best tactics of research and supporting them to perform researches help to enhancement of dissertations quality This needs a fundamental reform in long term planning for medical education