Hypothyroidism is a condition where there is a decrease or absence of thyroid hormone production as a result of a disorder occurring anywhere in the hypothalamo-pituitary-thyroid axis. There are very few studies in the literature reporting on the effect of hypothyroidism on lipid metabolism and carotid intima-media thickness (CIMT) in children. The present study was designed to determine whether hypothyroidism is associated with an increase in the CIMT and lipid levels in patients under thyroid hormone replacement therapy. The study included 30 children (under thyroid hormone replacement therapy) diagnosed with hypothyroidi and a control group comprising 30 healthy, euthyroid children. All the patients were examined for clinical characteristics, and the serum lipid levels and the CIMT were measured. Mean age was 8.47 ± 5.22 years in the patient group and 8.82 ± 4.91 years in the control group. Patient group TSH value was significantly higher than control group (9.95 ± 18.43, 1.93 ± 1.04, p = 0.021, respectively). The t otal cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and TG values were similar in both group (p = 0.065, p = 0.429, p = 0.219, and 0.391, respectively). CIMT values of the patient and control groups did not differ significantly (0.40 ± 0.08 and 0.39 ± 0.07, p = 0.920, respectively) In this study, contrary to the rare studies in the children's age group in the literature, no significant changes in lipid pr ofile and CIMT were detected in patients with hypothyroidism. Further prospective studies are needed to substantiate these findings in children with hypothyroidism.