Purpose: An international trial (formerly Ludwig Trial V) has been conducted in 1,275 subjects to ascertain if perioperative chemotherapy is beneficial for node-negative breast cancer patients and to identify subgroups of patients who benefit from this therapy. Patients and Methods: Node- negative breast cancer patients were randomized to receive either one cycle of perioperative chemotherapy or no adjuvant treatment. A detailed pathology review was conducted in 1,203 of the 1,275 patients enrolled. Stepwise Cox regression analysis was used to search for factors either predicting chemotherapeutic responsiveness and/or influencing disease-free survival (DFS). Results: As expected, primary tumor size, grade, and the presence of peritumoral vascular invasion are the most important prognostic factors. Perioperative chemotherapy provides a DFS advantage at 5 years of median follow-up and such treatment is more effective for estrogen receptor-negative than for estrogen receptor-positive tumors, for histologic grade 2 and 3 than for grade 1 tumors, and for patients in whom no axillary lymph node metastases were found even after serial sectioning and review by the Central Pathology Laboratory. Conclusion: Hormone receptor status and tumor grade are important factors for predicting responsiveness to perioperative chemotherapy in node-negative breast cancer.