Purpose: To diagnose benign and malignant breast lesions using elastography, which has proven useful and found increasing use in tumor diagnosis. Lesions with heavy blood flow must often be approached as possibly malignant. Elastography has also been used to evaluate potentially benign lesions, which are usually hypervascular. In this study, we examined such cases retrospectively to determine what points should be kept in mind during examination and testing. Subjects and Methods: Of patients who had undergone ultrasound evaluation from April to June 2007, whose B-mode ultrasound evaluation was category 3 or higher, and whose color Doppler ultrasound findings indicated heavy blood flow, those with an elastography score of 3 or lower served as subjects, and their ultrasound and histologic findings were studied. Results: Twelve of the 17 subjects had breast cancer; the remaining 5 had benign lesions. Eight of the subjects had an elastography score of 1 or 2: 4 had ductal carcinoma in situ; 1, papillotubular carcinoma; 1, fibrocystic breast disease; 1, intraductal papilloma; and 1, a phyllodes tumor. Of 9 subjects with an elastography score of three, 4 had ductal carcinoma in situ; 1, scirrhous carcinoma; 1, solid-tubular carcinoma; 1, papillotubular carcinoma; 1, fibrocystic breast disease; and 1, a phyllodes tumor. Of the 12 cases of breast cancer, 8 were cases of ductal carcinoma in situ and 4 were cases of invasive cancer. In 3 of the 4 cases, the invasive portion was relatively small and accounted for the image. Conclusion: Further study seems warranted by the fact that in cases that were potentially malignant according to B-mode and color Doppler ultrasound findings, lesions with an elastography score of 3 or lower were either non-invasive cancer or benign lesions.