A suboptimal dose intensity of adjuvant chemotherapy has been associated with a poor prognosis in patients with early-stage breast cancer. We investigated the relative dose intensity (RDI) of modern adjuvant chemotherapy regimens in patients aged ≥ 65 years. An RDI of ≥ 85% was achieved in 177 of 281 included patients (63%). Better supportive care of risk groups might further optimize the RDI. Introduction: Maintaining the relative dose intensity (RDI) of adjuvant chemotherapy at ≥ 85% has been associated with improved treatment outcomes in early-stage breast cancer (ESBC). Increasing evidence has suggested that patients aged ≥ 65 years can maintain the optimal RDI for standard chemotherapy regimens. The present study investigated the RDI of newer adjuvant chemotherapy regimens in this demographic. Patients and Methods: We retrospectively analyzed the data from 281 patients aged ≥ 65 years with a diagnosis of ESBC who had received adjuvant chemotherapy across 3 sites in Queensland, Australia from 2010 to 2015. The primary endpoint was the proportion of patients who had received an RDI of ≥ 85%. Results: The median age at diagnosis was 68 years (range, 65-85 years), with 36.3% aged > 70 years. The patient characteristics included tumor stage T3 or T4 in 17% and node-positive disease in 60%. The common chemotherapy regimens included docetaxel/cyclophosphamide (23%), 5-fluorouracil/epirubicin/cyclophosphamide plus docetaxel or paclitaxel (17%); Adriamycin/cyclophosphamide/weekly paclitaxel (38%); and docetaxel/carboplatin/trastuzumab (11%). Primary (15%) and secondary (54%) granulocyte colony-stimulating factor (G-CSF) was used. An RDI of ≥ 85% was achieved in 63% of the patients. Significant associations were noted between a reduced RDI and age ≥ 70 years (P <.001), Charlson comorbidity index ≥ 1 (P =.043), initial dose reductions (P =.01), secondary G-CSF use (P =.45), hospital admission (P <.001), and febrile neutropenia (P =.007). Treatment-related toxicities were the most common reason for noncompletion, with high rates of hospital admissions (46%) and febrile neutropenia (22%). Conclusion: Our findings suggest that patients aged ≥ 65 years with ESBC can maintain an optimal RDI with modern chemotherapy regimens. Appropriate geriatric assessment and the use of supportive measures such as G-CSF could better assist select groups to maintain an optimal dose intensity.