AbstractFingerprints from 200 women with histologically proven breast cancer (case group) were compared to fingerprints from 138 women with no history of any malignant disease (control group). Of the patterns analyzed, four were significantly associated with breast cancer: accidentals, transitionals, angled ulnar loops, and horizontal ulnar loops. A fifth print, the angled radial loop, was found to be of borderline importance as an independent predictor of breast cancer. Of 200 patients in the case group, 27 had one or more accidental prints, 58 had one or more transitionals, 34 had one or more horizontal ulnar bops, and 93 had one or more angled ulnar loop patterns. In 138 control subjects there were 2 with accidental patterns, 21 with one or more transitionals, 6 with horizontal ulnar loops, and 16 with one or more angled ulnar loops. In addition, there appeared to be a gradient of risk; a woman with one type of suspicious print is at higher risk of breast cancer than a woman with none, and two suspicious prints indicate a higher risk than does one. If these findings are confirmed, the prints described will represent a noninvasive anatomical marker of breast cancer risk.