Purpose: To investigate the additional value of DKI in discriminating suspicious breast lesions on DCE-MRI, as compared with conventional DWI; and to explore connection between DKI-parameters and prognostic factors of breast cancers. Methods: The institutional review board approved this retrospective study and written informed consent was waived. Totally, 300 women (mean age, 43.2 +/- 10.4 years) with suspicious breast lesions on DCE-MRI were enrolled from November 2014 to September 2019. With pathology as reference, performance of ADC, K-app and D-app in discriminating suspicious breast lesions were analyzed by receiver operating characteristic (ROC) analysis with area under ROC curve (AUC). The specificities of parameters were compared by Chi-square test. The ADC, K-app and D-app of breast cancers with different receptor status were compared using Student's t or Mann-Whitney U or Kruskal-Wallis test. Results: There were 344 suspicious breast lesions (220 malignant, 124 benign) in 300 women. No significant differences were found for AUCs of ADC and DKI-parameters in discriminating suspicious breast lesions (0.882 vs. 0.888, p = 0.480). The specificities were significantly higher with ADC and Dapp than that with DCE-MRI (p = 0.003 and 0.005). The ADC, K-app and D-app were correlated with HER2 expression and lymph node status, and ADC and K-app differed between ER-positive and negative tumors (all p < 0.05). Except K-app, DKI/DWI-parameters showed relation with Ki-67 expression. None of the DKI/DWI-parameters showed relation with lesion grade (all p > 0.05). Conclusion: The more complicated and time-consuming DKI is not superior to conventional DWI in differentiating suspicious breast lesions and reflecting prognostic information of breast cancer.