The purpose of this research is to trace the relationship between homesickness and the amount of perceived social support in the freshmen’s mental health. The present research uses correlations and cross-sectional study. The participants were 120 non-native undergraduate students [84 girls, 36 boys] of university of Guilan in the academic years of 2009-2010; they were selected randomly, and examined with Persian Homesickness, Vaux social support and Mental Health questionnaire. The data were analyzed by Pearson’s correlation and Stepwise regression. These analyses showed that there are significant negative relationship between total score of social support and mental health score and there are significant positive relationship between homesickness and mental health, and also the variables of adjustment, total scale of social support, homesickness and loneliness can predict the degree of freshmen’s mental health. The results showed that by raising the amount of social support, the freshmen’s mental health will rise, and by experiencing homesickness more, the freshmen’s mental health will decline.