A prophylactic bilateral subcutaneous mastectomy, following a preoperative mammogram revealed clustered small calcifications in the left breast. In order to investigate the merits of thermorphythmometry, the patient self-measured surface temperature of each breast, above and below the nipple, while awake. In the case here presented, bilateral subcutaneous mastectomy followed by extensive histologic scrutiny of both breasts revealed no indication of malignancy. Bilateral fibrocystic disease with calcification and lobular hyperplasia was found. As compared to the contralateral sites, the atypical epithelial proliferation was more abundant in the mammographically and thermorhythmometrically 'abnormal' area of the left breast.