Purpose: The purpose of this study was to compare stress levels of middle school students by grade. Methods: This was a descriptive comparative survey using as convenience sample of 701 1st, 2nd and 3rd-grade students. The stress levels was measured by stress scale that consisted of 65 items regarding personal characters family, school, and peer factors. The data were analyzed by ${chi}^2$-test, t-test, ANOVA, and multiple regression using the SPSS/WIN 12.0 statistical program. Results: 1st graders and female students showed higher stress levels than 2nd, 3rd graders and male students, respectively. Conclusion: Grade, gender, life satisfaction, and regional levels were all significant factors associated with high stress levels among middle school students. Development of stress management program for this specific population, especially targeting students who are 1st Grader and living in rural areas, is needed.