Background and Aim: Citation could be considered as basis of scientific researches. Each researcher will use citation to prove his scientific findings either to be in correspondence with truth or to familiarize readers with more references. Maintenance and continuation of informational link by citation is essential. Theses are not exceptional for this subject. This study was done to review the accuracy of cited articles of specialized theses (Tehran University of Medical Sciences in 1386) and the rate of correspondence with Vancouver style.

Materials and Methods: Citation analysis is used as study approach. By systematic sampling and Morgan table 357 cited articles were selected to review for accuracy of citation and their correspondence with Vancouver style. Six studied factors are as following: Name of author(s), title of article, title of journal, year of Publishing, volume number, number of pages. Citation errors are divided in to two main groups: 1-Minor errors 2-Major errors. Method of sampling is direct observation. Data was entered in a check list, based on Taylor division. SPSS(11.0) software was used to analysis.

Results: Out of all 357 reviewed cited articles, totally 111.4% citation errors were observed and only 136 (38.09%) of citations had no error and 221(62%) citations had errors. 9.8% of citations fully corresponded with Vancouver style.

Discussion and Conclusions: Main reasons of dissatisfying results of citation errors and rate of correspondence with Vancouver style are as follows: Student's unawareness of importance of scientific researches consistence Laxity of students about citification produce, inaccessibility to original references and copy of other sources. Teacher's less emphasis on accuracy of citation, carelessness of educational universities about accuracy of citation in thesis, not use of experts and specialized librarians for consultation, being not familiar with reference management software.