Axillary lymph node involvement in breast cancer is associated with higher risk of distant metastasis and recurrence. This study evaluated whether MRI can be used to longitudinally monitor effects of neoadjuvant chemotherapy on axillary lymph nodes in situ. Nodal volume and compacity were analyzed with respect to treatment responders and non-responders. Comparisons with unaffected nodes were made. Neoadjuvant chemotherapy significantly reduced nodal volume of the affected nodes in both responders and non-responders. Nodal volumes of the responders normalized whereas those of the partial-responders did not normalize completely. This approach may prove useful for monitoring cancer treatment effects on nodal morphology.