Objective: The aim of our study was to investigate whether platelet indices were affected in patients with Hashimoto's thyroiditis (HT). Method: 11 patients (10 female, 1 male) with HT and 26 subjects with nodular goiters (19 female, 7 male) selected as control group were included in the study. All cases were examined for complete blood count parameters (leukocyte count, neutrophil count and percentage, lymphocyte count and percentage, platelet count, plateletcrit, platelet distribution width (PDW), and mean platelet volume (MPV)). Results: Leukocyte count, neutrophil count and percentage, lymphocyte percentage, platelet count, plateletcrit, and MPV in the patient group were not statistically different from the control group. Lymphocyte count and PDW were significantly higher in patients with HT than in the control group. Conclusion: Our results suggest that patients with HT have higher PDW levels. Increased PDW in HT may be helpful in diagnosis, floow-up, and prognosis of the disease.