In this study, 211 M. S. theses written by students of Irrigation in Shahid Chamran University of Ahvaz, Tehran University, Shiraz University and Ferdowsi University of Mashhad have been examined. The article aims at identifying the authors, books and periodicals frequently referred to, the average number of citations used in each thesis, the number of citations regarding information sources and finally the authorship pattern of papers published in periodicals.To achieve this objective, 7827 citations used in these theses were extracted and studied. The findings indicate that in these four universities, periodicals are used as the major source of reference by students of irrigation. Findings concerning the authorship pattern of articles published in periodicals, indicate that Persian articles are foremost single-authored, contrary to non- Persian articles. Regarding the language of the sources, the findings indicate that 70% of the sources used are in English and the rest (30%) are in Persian.Furthermore, the average number of citations used in the examined theses in these universities was found to be 38. In this respect Ferdowsi University of Mashhad, with an average of 70. 60 citations for each thesis, constitutes the upper end of the scale whereas Tehran University, with an average of26. 90 citations constitutes the lower end of the scale.Finally, recommendations are made to the agricultural Libraries as well as to the writers of Persian articles.