Background: Considering the important role of happiness in mental health, the vulnerability of students and also moving toward a positive-oriented approach of psychology, this study was carried out to evaluate the level of students' happiness and its related factors.

Materials and Methods: This cross-sectional study with a census type sampling was done on the undergraduate first year students of Kashan University of Medical Sciences (No=1444). The questionnaires were filled out by all eligible students during the first month of the semester. The standard Oxford test and a researcher-invited questionnaire were used to measure the level of happiness and the related factors in respectively. Chi-square, Independent t-test, ANOVA and were used to analyze data statistically.

 Results: 78.7% of participants were girls and the rest were boys. The mean value of happiness among the students was 42.57±13.96. There was a statistical correlation between happiness and factors like: gender, economic status, extracurricular activities, hopefulness for future occupation, academic education satisfaction, mean score of courses, current living place and stress status during last year, but no relation was found with age, marital status, types of academic education (formal/informal), domesticity of students, level of family education and wealth, number of brothers and sisters, birth order, job and financial income. The mean value of happiness among females was more than that in males.

Conclusion: Paying attention to high-risk students, especially females, with poor economic status, and student under stress and low scored in courses is a mandate.