Introduction: Strengthening the spirit of religiosity and developing the financial resources of students increase their optimism, which is followed by an improvement in their performance and promotion of the educational system of the country. The current research was performed to determine the correlation of optimism with religious beliefs and social support among students. 
Materials and Methods: This descriptive-analytical study was conducted at Golestan University of Medical Sciences in 2014. The study sample was selected through convenience sampling and determined to be 327 students by Morgan formula. The data were collected by religiosity measure, social support and optimism scales, and analyzed by independent t-test and Pearson correlation coefficient.
Results: The results showed a significance level for all the research questions (P<0.05) at 95% confidence level and 5% measurement error with DF=325. There was a significantly positive correlation between religious beliefs and social support, and optimism among students. Since the correlation coefficient between research variables was r=0.783, it showed a positively high correlation between variables. Moreover, the findings of regression analysis showed that religious beliefs, with β=0.532, had the maximum level of correlation with optimism in students. 
Conclusion: The findings indicated that with a rise in religious beliefs and social support, optimism was increased in students of Golestan University of Medical Sciences. Furthermore, religious beliefs had a more predictive ability in optimism than social support.