Using gadolinium-DTPA enhanced MRI we analyzed the enhancement characteristics of palpable breast masses in 23 patients--10 cancers and 13 benign lesions. The most specific finding for separating benign from malignant lesions was a ratio of maximum intensity change divided by the time interval during which this first occurred. Designated ranges of this ratio were specific for benign disease and sensitive for malignancy in this small patient group. Three of eight fibroadenomas exhibited enhancement patterns indistinguishable from cancer.