Abstract: Objective To investigate the reasons of elevated alanine aminotransferase in college freshmen. Methods Total of 494 freshmen admitted from 2010 to 2014 were enrolled and divided into two groups, elevated alanine aminotransferase (ALT) group (297 cases) and normal ALT group (200 cases). The incidence of fatty liver, overweight and obesity rate were analyzed between the two groups. Results The freshmen with elevated ALT exhibited a significant increase in the incidence of fatty liver and obesity when compared to the freshmen with normal ALT. Conclusions Fatty liver induced by obesity may be the main cause of elevated ALT in the college freshmen.