The aim of this work was to evaluate the value of contrast enhanced MRI for determination of response to neoadjuvant chemotherapy (type FEC) in breast cancer according to two parameters: size of the enhancing tumor and the maximum relative enhancement curve (MRC) in the same tumor area. Twenty women with breast cancer (15 invasive ductal carcinomas and 5 invasive lobular carcinomas) T2 (n = 8) or T3 (n = 12) were evaluated by physical examination and MRI after a minimal of three courses of FEC and prior to surgery. Data from physical examination and imaging studies were compared to histopathological findings. Physical examination estimated correctly the residual tumor size in 45% of cases and MRI in 60% with 3 false negative cases. Among evaluated patients with MRI measurable residual tumor, tumor size was underestimated in 69% of the cases and overestimated in 31% of the cases. A MRC flattening was observed in 5 cases among the patients with a partial response or clinical stable disease correlated with a poor cellular density in the microscopic findings. MRI monitoring of chemotherapy response can be useful for guiding surgery. Therefore, underestimation of the residual tumor size and false negative rate are remaining problems.