Background: Approximately 1–2% of the adult population in developed countries has Heart Failure, with the prevalence rising to ≥10% among persons 70 years or more. Most of the molecular and cellular mechanisms responsible for the cardiovascular effects of thyroid hormone have been clarified. Thyroid hormones produce changes in cardiac inotropism and chronotropism more rapidly than would be expected from regulation of gene expression. Hypothyroidism causes cardiac atrophy, due to decreased αMHC expression and increased β MHC expression. Moreover, hypothyroidism also leads to chamber dilatation and impaired myocardial blood flow [1]. Material and Methods: 200 patients between age group of 45 to 75 yrs, presented in medical emergency and medical outdoor of the institution with heart failure were studied. Comparison of Thyroid Profile and LVIDd (Left Ventricular Internal Diameter at Diastole) was done at Baseline, 3 months and 6 months. Results: After comparing the thyroid profile and 2DEchocardiography findings in subclinical hypothyroidism of treated group after 6 months, there was increase in TSH and fall in FT4 (p 0.001) with a significant improvement in LVIDd. Conclusion: There was improvement in EF, a decrease in LVIDd, increase in Mitral E velocity, decrease in Mitral A velocity and increase in E/A ratio in cases as compared to controls with treatment