Objective To determine the diagnostic potential of Diffusion-weighted MR Imaging to differentiate between benign and malignant breast lesions by comparing apparent diffusion coefficient (ADC) among normal breast tissue, benign and malignant breast lesions. Methods Retrospective analysis of 177 pathologically confirmed breast lesions examined using EPI-DWI and compare the mean ADC among normal breast tissue, benign and malignant breast lesions. The cut-off ADC value for malignant lesion was determined using receiver operating characteristic (ROC) curve analysis. The diagnostic accuracy of DWI was compared in breast mass and non-mass lesions. Results Mean ADC values for benign(112/177), malignant(65/177) breast lesions and normal breast tissue(177) were (1.57±0.25)×10-3mm2 /s, (1.11±0.32)×10-3mm2 / s and (1.72±0.22)×10-3mm2 /s, respectively. With a cut-off value of 1.23×10-3mm2 / s for ADC in ROC analysis, 80.42% sensitivity and 92.13% specificity were achieved. Among 177 lesions 144 were mass and 33 were non-mass. The mean ADC of malignant mass lesions [(1.06±0.27)×10-3mm2 /s] was statistically lower than that of benign ones [(1.58±0.26)×10-3mm2 /s]. The sensitivity and specificity of the ADC with a threshold of [1.23×10-3mm2 /s] was 85.17﹪ and 92.84﹪respectively. The mean ADC of malignant non-mass lesions [(1.25±0.40)×10-3mm2 /s] was statistically lower than that of benign ones [(1.50±0.18)×10-3mm2 /s]. The sensitivity and specificity of the ADC with a threshold of [1.36×10-3mm2 /s] was 77.81﹪ and 80.35﹪respectively. Conclusion The ADC is an effective parameter in distinguishing between malignant and benign breast lesions. The cut-off values of ADCs are different between mass and non-mass lesions. DWI of the breast can help differentiate benign and malignant breast lesions from normal breast tissue.