Aim: To evaluate whether subclinical hypothyroidism (SH) is associated with anthropometry and fatty infiltration of liver in obese adolescents. Materials and methods: The adolescents attended with the complaint of obesity aged 11 to 15 years included in the study. Patients were diagnosed as obese adolescents with fatty liver. Age-, gender-, and body weight-matched obese adolescents without fatty liver seen during the same period served as controls. Clinical characteristics, laboratory parameters, and frequency of subclinical hypothyroidism (SH) of both groups were compared. Results: The study population included 218 adolescents with obesity. Of 218, 30 (13.7%) had fatty liver at ultrasonography (group 1) and the remaining 188 obese adolescents did not have fatty liver and served as control (group 2). The mean ages of groups 1 and 2 were 12.7 ± 1.25 and 13 ± 1.39 years; the rate of female participants were 43.3% and 55.8%; and, weight:height ratios were 157.2 ± 24 and 151.3 ± 19.8 (P = 0.37, 0.24, and 0.54, respectively). The prevalence of SH in patients with fatty liver was 10% and was not significantly higher compared to the controls (6.4%, P = 0.55). Conclusions: SH seems to be a secondary condition rather than a triggering factor for development of fatty liver in adolescent obese patients. There was no statistically significant relation between subclinical hypothyroidism and fatty liver. © TÜBİTAK.