INTRODUCTION :This study was conducted to assess utility of Ki67 as proliferation marker in thyroid lesions and for usefulness of Ki–67 in distinguishing benign and malignant thyroid lesions. MATERIALS AND METHODS In present study 50 cases of non– and neoplastic thyroid lesions were included. Histopathological diagnosis achieved on gross and microscopy of h&e stained slides followed by Ki–67. RESULTS In present study Ki67 labeling index were counted. Range of Ki67 LI for multinodular goiter is 0.1 to 0.9 and mean 0.29. For Hashimoto thyroiditis range was 0.3 to 0.6 & mean 0.42. In follicular adenoma range was 0.6 to 1.4 and mean 0.9. Range of Ki67 LI for Papillary carcinoma was 2.6 to 4.9 and mean 3.7. For Follicular carcinoma range was 4.6 to 9.1 & mean 6.6. Ki67 LI was much higher in Anaplastic carcinoma i.e 35. CONCLUSION There was statistically significant difference in benign and malignant thyroid lesions.