Background: Breast cancer often presents with signs such as high-density masses. The description of high-density masses remains controversional as a descriptor of malignancy. Histopathological assesment, including the Nottingham Grading System, is considered the gold standard for determining the definitive diagnosis of cancer. Objective: To determine the comparative study of mass density according to BI-RADS mammography and histopathological grading in breast cancer at Dr. Soetomo Hospital Surabaya January 2017 – December 2021. Methods: This study compares mammography medical records of breast cancer diagnoses in patients from January 2017 – December 2021 at Dr. Soetomo Hospital Surabaya, based on histopathology. Its an analysis study focused on observational and comparisons. Results: The number of cases according to breast cancer inclusion data  was 261 data. Breast cancer patients were predominantly in the age group of 50 – 54 years (20.3%) and the majority of masses were found in the right breast (53.3%). The most common type of mass density was high density (46.7%) and the most frequent histopathological grading was grade 3 (51.3%). The comparison of age between mass densities showed a p-value of 0.71 (p > 0.05), while the comparison of mass densities between histopathological grading had a p-value of 0.058 (p  >  0.05). Conclusion: Most breast cancer patients at Dr. Soetomo Hospital Surabaya from January 2017 – December 2021 were aged 50 – 54. High density masses were common and grade 3 was the highest histopathological grade. Age didnt differ much between equal and high density masses. The same applied to mass density among histopathological grading.