© 2015, Association of Otolaryngologists of India.Obstructive sleep apnea syndrome (OSAS) is associated with fatty liver disease. In the present study, relations between alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and the severity of OSAS and polysomnography parameters were investigated. The study included 194 patients with OSAS and 114 control patients. The patients underwent an overnight polysomnography (PSG) in the Sleep Laboratory. ALT and AST levels were compared between the patients and the controls and between the subgroups of the patients. ALT and AST levels were also compared with the PSG parameters REM AHI, NREM AHI and minimum O2 saturation separately. The mean ALT was 28.95 in the patients and 17.85 inthe controls (p < 0.001) with a statistically significant difference and the mean AST was 23.62 in the patients and 16.53 in the controls with a statistically significant difference (p < 0.001). The patients with OSAS had significantly higher ALT and AST levels. The higher the ALT and AST levels were, the more severe the disease was, though the differences between the subgroups of the patients were not significant.