Background: It has recently been demonstrated that vitamin D, long thought to be a hormone that regulates calcium and phosphate, is essential for the treatment of a number of non-skeletal illnesses, including cardiovascular disease. Numerous research have been conducted on the connection and potential causal involvement of vitamin D in cardiovascular diseases and the well-known risk factors associated with them. There aren't many research conducted in this region of the world, though. This study's primary goal was to measure the 25-hydroxyvitamin D levels in heart failure patients. Methods: This was a institute based Observational Cross Sectional Study, done at General Medicine Ward, Department of General Medicine, Burdwan Medical College and Hospital, West Bengal, India, from March 2021 to May 2022. Total 100 patients with heart failure and fulfilled the inclusion criteria were included in this study data were entered into a Microsoft excel spreadsheet and then analyzed by SPSS (version 27.0; SPSS Inc., Chicago, IL, USA) and Graph Pad Prism version 5. Result: In present study maximum participants 57 (57%) were from the age group of 61-80 years. Mean age of the participants was 65.38±13.7656l. In our study, 46 (46.0%) patients were Normal BMI, 14 (14.0%) patients were Obese BMI and 40 (40.0%) patients were Overweight BMI. In the present study 100 (100%) of the participants had Exertional Dyspnoea followed by PND and fine crepts 79 (79%) each. Vitamin D ≤30 was present in 88 (88%) off study population and >30 was present in 12 (12%) of study population. Conclusion: In our study we found that 88 out of 100 study participants were Vit D deficient. It was also found that, 25(OH) Vit D levels had negative correlation with LVEF