To compare cardiovascular risk factors in obese patients with or without Subclinical Hypothyroidism (SH), also to estimate the prevalence of SH in obese children and adolescents. Method: A total of 226 obese children and adolescents aged 6-18 years were included in the study. Two groups were created as euthyroid group (n=195) and SH group (n=31). After an 8-12 hour overnight fasting, serum blood glucose, insulin, HDL, LDL, cholesterol, triglyceride TSH, free T4, ALT, AST levels were measured. HOMA-IR and atherogenic index (AI) were calculated. Results: Prevalence of SH was estimated as 14.1 %. The values of fasting glucose, fasting insülin, ALT, AST, TSH, HOMA-IR levels were significantly higher ın SH group than euthyroid group. There was a positive correlation between TSH and fasting glucose, insülin, triglyceride, ALT, AST, HOMA-IR, AI. It was also demonstrated that the TSH level was significantly and independently related to HOMA-IR value ın multiple regression analysis (p=0.001). Conclusions: Obese patients with SH may be more susceptible to metabolic complications than euthyroid subjects.