The purpose of this study was to investigate the relationship between religious attitude and academic performance in terms of the mediating role of academic stress among students of Guilan University. The study population was all undergraduate students of the University of Guilan (19953) among whom the 376 subjects were selected by simple stratified random sampling method using Krejcie and Morgan table. To collect desirable data, the following questionnaires were used: Religious Attitude Questionnaire by Khodayarifard, et al (1388); Academic Performance Questionnaire by Dortaj (1382); and Academic Stress of College Students by Gadzella and Baloglu (2001). Data analysis was performed using structural equation modeling method and Amos software. The conceptual model of the research was fitted to confirmation and then the standard regression coefficients of the model were explained. The findings showed that religious attitude has a positive direct effect of 0.32 on academic performance and also an indirect positive effect of 0.048. Therefore, religious attitude, in addition to having a positive effect on academic performance, improves this performance in students by reducing academic stress. Therefore, the authorities are advised to make more efforts to strengthen the religious attitude of students to increase the academic performance and reduce the incidence of academic stress.