Study of hypothyroidism and its relationship to the levels of the hormone hepcidin and C-reactive protein in people treated with levothyroxine. This study was carried out between November 2022 and March 2023. The study had a total of 90 male and female participants with an average age of 25 to 50 years old. All samples were obtained from both hospitals in Baghdad and the Medical Lab. The diagnosis of hypothyroidism based on symptoms and the hypothyroidism control test score led to the collection of 30 samples from healthy individuals, 30 from those with untreated hypothyroidism, and 30 additional samples. From people with hypothyroidism who were treated with levothyroxine, where the necessary tests were conducted for the three groups, Blood samples were collected in a gel tube, and serum was separated for use in their respective measurements of (TSH, T3, T4, CRP, and hepcidin. According to the results, there were no significant differences in the mean patient’s age (p=0.419) or gender distribution (p=0.638) between the three studied groups. When thyroid function tests were done on the groups that were studied, the hypothyroid patients had significantly lower levels of triiodothyronine (T3) and thyroxine (T4) and higher levels of thyroid-stimulating hormone (TSH) before treating them (p< 0.001).  And the highest serum hepcidin and CRP levels (11.77 ± 0.98 and 14.61 ± 2.49 respectively) were found in group 1 patients. On the contrary, the lowest levels (7.61 ± 1.56 and 3.19 ± 0.29, respectively) were present in group 2 patients. In healthy subjects, the hepcidin and CRP levels were 8.45 ± 0.53 and 3.51 ± 0.91, respectively.Accordingly, there was a significant difference in hepcidin and CRP levels between the three studied groups, and the results showed a decrease in hepcidin and C-reactive protein after treatment.