Abstract Background: Breast cancer is the most commonly occur-ring cancer in women and one of the most important causes of death. 1.67 million new cases of breast cancer were iden-tified worldwide, accounting for 25% of all cancers. The incidence and mortality rates of breast cancer is rising. Patient survival rates depend on both early diagnosis and improved treatment modalities including surgery, radiotherapy and chemotherapy. Aim of Study: To investigate the accuracy of dynamic contrast material-enhanced (DCE) breast MRI for determining residual tumor size after neoadjuvant chemotherapy (NAC) and detect the value of measuring residual size in delayed phase compared to early phase. Patients and Methods: The study started at December, 2019 and included twenty female patients who were newly diagnosed breast cancers after completion of NAC referred from surgical oncologists to Radiodiagnosis Departments of Ain Shams University and Nasser Institute Hospitals. Each patient was subjected to full history, reviewing medical sheet and dynamic contrast enhanced MRI using 1.5 T unit (GE). Results: DCE-MRI after NAC underestimation rate was found to be about 50% Vs 15% overestimation rate. 51% NPV Vs 93% PPV was reported. Delayed phase better correlated with postsurgical histopathological size than early phase. Conclusion: DCE-MRI has lower accuracy when per-formed after NAC. It tends to underestimate residual tumor size. Delayed phase is more accurate than early phase in evaluating residual tumor size.