Abstract : Recent studies showed that microRNA has post-transcriptional effects and is considered an important cause of autoimmune diseases. MiRNA is one of the most important associated with Hashimoto's autoimmune disease, in which T cells proliferate and cause the production of thyroglobulin antibodies that damage the thyroid gland and affect its function. This study aimed to find the relationship between miRNA 125a-5p in Hashimoto's thyroiditis and thyroglobulin antibody production. In which 125 patients were diagnosed. The ratio of males to females was 20-80%, aged between 16-78 years. These samples were collected from the Specialized Center for Endocrinology and Diabetes/Al-Rusafah-Baghdad/ Iraqi Ministry of Health. Hashimoto's patients were diagnosed using clinical, ultrasound methods and serological tests. The serum used for detection (Anti Tg-Abs) was separated and Hashimoto's patients were diagnosed using ELASI technology. The blood of the microRNA 125A-5p set of 40 samples was accounted for by quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The results showed a decrease in miRNA-125a-5p expression compared with (10) healthy individuals. The study showed high levels of (Anti Tg-Abs) test with statistically significant differences (P≤0.01) compared to healthy subjects.