Background: Heart failure (HF) is a clinical syndrome that affects individuals who have an inherited or acquired abnormality of their heart's structure and/or function. The present study was conducted to evaluate serum parathyroid hormone levels and its relation with severity and duration of heart failure. Materials & Methods: The study was conducted at Department of Medicine, Patna Medical College and Hospital, Patna during June 2022 - Dec 2022. 45 patients with CCF of both genders underwent 2- D echocardiography. Parameters such as ejection fraction, and NYHA grading. Serum parathyroid hormone levels were measured by chemiluminescence immunoassay technique. Results: Out of 45 patients, males were 25 and females were 20. Out of 24 patients with EJ <35%, 13 had serum PTH >72pg/ml and 9 had <72pg/ml. 11 patients with EF 35-40, all had serum PTH >72pg/ml. 10 with EJ >40, all had serum PTH >72pg/ml. Out of 23 grade II patients, all had serum PTH >72pg/ml. Out of 22 grade II patients, all had serum PTH >72pg/ml. Out of 25 patients with duration 1-2 years, 24 had serum PTH >72pg/ml and out of 20 patients with duration >2 years, 12 had serum PTH <72pg/ml. The difference was significant (P< 0.05). Conclusion: Serum PTH and other serum-derived biomarkers of cardiomyocyte necrosis are linked to higher rates of cardiac morbidity and mortality both inside hospitals and outside.