Background: Digital mammography (DM) is one of the most common and effective radiological methods for breast cancer screening and detection. A dense fibroglandular breast tissue can lead to false negative results by superimposing on the lesion margins. Therefore, adjunctive imaging methods, such as digital breast tomosynthesis (DBT) and ultrasonography (US), are needed to increase mammographic sensitivity. Objectives: This study aimed to examine the contribution of US and DBT to DM in different patient groups (patients group of breast imaging-reporting and data system [BIRADS] 0 and 3-4 lesions, patients with dense breast parenchyma, patients with non-dense breast parenchyma).. Whether US and DBT can upgrade or downgrade the BI-RADS category of uncertain lesions detected on DM was also investigated. Patients and Methods: Forty-six patients, who were classified as BI-RADS categories 0, 3, and 4 in DM, according to DBT and US findings, were included in the study. DM followed by DBT was performed for the patients, and the BI-RADS classification system was applied. Subsequently, the patients were evaluated sonographically, and the BI-RADS system was applied according to the US results. Each BI-RADS category was compared with the histopathological and multimodality follow-up results. The diagnostic performance of all modalities was also examined alone and in combination. Results: The sensitivity and specificity of DM alone was 42% and 87%, respectively. DBT detected the lesions with 92% sensitivity and 68% specificity. The modality with the highest sensitivity for the detection of malignant lesions was US (100%). Besides, the specificity of DBT was significantly high for dense breasts (P < 0.001). There was no significant difference in terms of the diagnostic accuracy of US measurements between dense and non-dense breasts. For indeterminate lesions, the integration of DBT and US to DM increased the diagnostic accuracy. Conclusion: The contribution of DBT is more valuable than US in patients with dense breast parenchyma.