METHODS The aim was to study the changes in thyroid antibody and T lymphocyte subsets after radiofrequency ablation (RFA) of thyroid nodules in patients with autoimmune thyroiditis. METHODS Patients (n = 135) with autoimmune thyroiditis and thyroid nodules were treated by RFA. The indices of thyroid function and thyroid antibody and T lymphocyte subsets were examined preoperation and on the 1st day and the 1st month after ablation. Any complications were recorded. METHODS The software SPSS 17.0.0 (version: 2008-8-23) running under Windows 8 was used for statistical analysis. The measurement data were expressed as x ± s, with P < 0.01 indicating a significant difference in the statistical data. RESULTS Levels of free triiodothyronine, free thyroxine, and thyroid-stimulating hormone were in the normal range before ablation, and no significant changes occurred on the 1st day or in the 1st month after ablation. The change in the percentage of CD8+T cells and the absolute value of B cells were not statistically significant (P > 0.01), and the values were in the normal range. Compared with values recorded preoperation, the value of TG-Ab, TPO-Ab, CD4+/CD8+, the percentage of CD4+T cells, the absolute values of lymphocytes, T cells, CD4+T cells, and CD8+T cells decreased significantly at the 1st day after ablation (P < 0.01) and then recovered to preoperative levels during the first 30 days after ablation (P > 0.01). Within 1 month after ablation, none of the patients had complications such as active bleeding, infection, recurrent laryngeal nerve injury, parathyroid gland injury, skin scald, and so on. CONCLUSIONS After RFA of thyroid nodules in patients with autoimmune thyroiditis, thyroid function is not affected and no serious complications occurred. TG-Ab and TPO-Ab levels can be significantly decreased, and the distribution of T lymphocyte subsets can be changed in the short term after ablation.