Background: Mammographic density has been shown to be a strong independent predictor of breast cancer and a causative factor in reducing the sensitivity of mammography. The risk of breast cancer related to changes in breast density over time, including its regression and persistence, remains controversial. The present study was done to evaluate the impact of malignancy on Breast Density. Material & Methods: Present study was conducted in the Department of General Surgery and Radio diagnosis IGMC Shimla from 1st July 2018 to 30 June 2019. A total of 60 were included and evaluated in the present study. These patients were divided into two groups. Group (A) included 30 patients with biopsy proven carcinoma of the breast while Group (B) included 30 patients with benign breast lesions or pain breast. Results: The mean age of patients presenting in Group A was 55.4±10.9 years and the mean age of the patients presenting in Group B was 54±9.84years respectively. In Group A of 30 cancer patients, majority of patients i.e 21patients (70%) had breast density of Type B. In Group B also, majority 20 patients (66.7%) had breast density Type B. In Group A out of 30 cancer patients, 10patients (i.e.33.3%) were BIRADS 4, 14 patients (46.7%) were BIRADS 5 and 6 patients (20%) were BIRADS 6. In Group B out of 30 patients, 6 patients (i.e.20%) were BIRADS 1, 12 patients (40%) were BIRADS 2 and 12 patients (40%) were BIRADS 3. In Group A of 30 cancer patients ,27 patients were diagnosed with duct cell carcinoma (90%) while 2 patient were reported as lobular carcinoma (6.7%) and 1 patients was diagnosed with tubular carcinoma(3.3%) . In Group B out of 30 patients, 2 patients (6.7%) were diagnosed as acute mastitis, 19 patients (63.3%) were diagnosed as Fibro-adenosis, 3patients (10%) were diagnosed as Fibro-adenoma. Conclusion: Maximum patients in this study were in the age group of 40-60year .Most breast cancer patients had higher BIRADS 5&6 , had breast density of Type B and majority of were reported as Duct Cell Carcinoma. Most of the benign breast disease patients had BIRADS2&3, had breast density of Type B and majority of were reported as Fibro-adenosis.