To investigate the relationship between elevated serum alanine-transaminase (e-ALT) and persistent rotating shift work (p-RSW) among employees with sonographic fatty liver (SFL), the authors performed a retrospective analysis on a cohort of electronics manufacturing workers. The records of 758 workers (507 men, 251 women) with initially normal ALT and a mean age of 32.9 years were analyzed. A total of 109 workers (14.4%) developed e-ALT after 5 years. Compared with those having neither initial SFL nor p-RSW exposure, multivariate analysis indicated that employees who had initial SFL but without p-RSW finally had a higher risk (odds ratio = 2.9; 95% confidence interval [CI] = 1.7-5.1) for developing e-ALT; workers with baseline SFL plus p-RSW had a 3.7-fold increased risk (95% CI = 1.8-7.5). SFL poses a conspicuous risk for the development of e-ALT, and persistent p-RSW exposure significantly aggravates the development of e-ALT among on-site workers with preexisting SFL.