Background: One of the most important topics in clinical psychology is finding and measuring of independent tools that have the same results for the evaluation of a psychological characteristic. There are only few studies that have examined the agreement between these methods. This study aimed to compare the three screening instruments for mental disorder among students of Kashan University of Medical Sciences during 2011-2012.

Materials and Methods: In this cross-sectional study, 983 students of Kashan University of Medical Sciences were selected using simple random sampling during 2011-2012. Students were asked to complete three mental health questionnaires including GHQ-28, BSI and MMPI. Data were analyzed using SPSS software.

Results: Findings showed that the prevalence rates for mental disorder based on the GHQ-28, BSI and MMPI questionnaires were 39.1%, 44.8%, and 44%, respectively. Correlation coefficients for GHQ-28 with BSI, GHQ-28 with MMPI and BSI with MMPI were 0.588, 0.488, and 0.533, respectively. The corrected classification of GHQ‌28 with BSI was 73.3%, GHQ‌28 with MMPI 71.5% and MMPI with BSI 69.8%. Kappa coefficient showed high level of agreement between the three tests.

Conclusion: According to the results of the study, there is a relatively high correlation between the three instruments in diagnosis of mental disorder among the students.