Abstract: Objective To evaluate the effects of intravenous gadolinium-DTPA on the diffusion-weighted imaging(DWI) of the breast. Methods A total of 40 women with 44 mass-like breast lesions were examined using 1.5-T MRI. The signal-to-noise ratios(SNRs) of the normal breast and the lesions, the contrast-to-noise ratios(CNRs), apparent diffusion coefficient(ADC), and exponent apparent diffusion coefficient(eADC) values of each lesion were measured from the DWI images before and after contrast enhancement. Results The SNRs and CNRs of the DWI images before and after contrast enhancement were not significantly different. In addition, no significant difference between the ADC and eADC values before and after contrast enhancement was observed in the benign lesions, whereas the opposite was observed in the malignant lesions. Conclusions The application of DWI after contrast enhancement is feasible in characterizing lesions in the breast. After contrast enhancement, the ADC values were significantly lower, and the eADC values were significantly higher in breast carcinomas. DWI after contrast media may improve the diagnosis of malignant breast lesions.