Aims: Thyroid gland is composed of spherical follicles and thyroid parenchyma includes two major cell types, the thyrocytes releasing thyroid hormones and C cells secreting mature calcitonin. Hypothyroidism and Hyperthyroidism both have been, known to be associated with the various abnormalities of the coagulation system. Our study, had been purposed to investigate the relationship between Mean platelet volume, platelet distribution width and plateletcrit with T3, T4, TSH levels of the patients. Methods: A retrospective evaluation was conducted on 90 patients (age group from 30 to 45 years) diagnosed with hypothyroidism (n=30), hyperthyroidism (n=30) and euthyroid (n=30) for over 6 months from October 2020 – March 2021. The demographic data and T3, T4, TSH values was obtained from the patients lab reports in Saveetha Medical College and Hospital. These values was correlated with platelet indices of MPV, PDW and PCT obtained by Sysmex-XN 1000 automated analyser. Result: Females population was predominant in both hypothyroidism and hyperthyroidism. On comparison of hypothyroid patients with euthyroid revealed statistically increase significant difference in plateletcrit. On comparison of hyperthyroid patients with euthyroid revealed statistically significant increase in Platelet count, MPV and plateletcrit. Conclusion: The present study, suggest that platelet parameters can be considered as a reliable markers and can be used as CVD risk evaluation parameters in hypothyroid and hyperthyroid patients due to abnormal thrombovascular activity.