Aim: Hashimoto's thyroiditis (HT) is a chronic autoimmune thyroid disease in which genetic and environmental factors play a role in the etiology. In addition, it remains the leading cause of hypothyroidism throughout the world. The neutrophil/lymphocyte ratio (NLR) is a cheap, simple measurement that can be used to indicate systemic inflammation associated with this disease. Materials and methods: 81 patients diagnosed with Hashimoto's thyroiditis and 54 healthy individuals were enrolled in the study. We recorded the results of the free triiodothyronine (FT3), free thyroxin (FT4), thyroid-stimulating hormone (TSH), anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin (anti-TG), complete blood count (CBC), and C-reactive protein (CRP) measurements in both groups and also calculated the NLR. Results: The NLR was statistically significantly higher in the HT patients than the controls (2.37±1.46 versus 1.80±0.67, respectively; p<0.003). Furthermore, a negative but statistically insignificant correlation was determined between the NLR and anti-TG and anti-TPO. Conclusion: NLR can be a valuable, practical parameter for monitoring HT as well as other autoimmune and chronic inflammatory diseases.