We have previously reported successful classification of breast cancer vs. benign breast tissue using Cole Relaxation Frequency (CRF) values calculated from impedance measurements on ex-vivo breast tissue samples at the time of surgery. Subsequent analysis of outcomes from follow-up medical visits of patients from this cohort provided evidence that the CRF values measured for tissue determined to be cancerous at the time of surgery correlated well with three possible outcomes for the patients (No Recurrence of Cancer; Recurrence with No Metastasis; and Recurrence with Metastasis). We present here data from a small (n=50) IRB approved study to classify and spatially map cancer and benign regions in the breast in vivo. Apparatus consisting of two parallel plates mounted on a conventional mammography gantry was used for these measurements. A portion of one of the plates was arranged in a 16 × 16 array of 256 separate regions for measuring the constant voltage impedance sampled at each electrode. Utilizing the patients’ pathology and radiology reports we found that the procedure correctly classified benign breast disease or cancer (including invasive and non-invasive ductal or lobular carcinoma) at the location of a suspicious mass, without apparent interference from density of the breast tissue. This approach was shown to be useful for identifying and spatially mapping electrically anomalous regions using the CRF as the classifier.