Background: The purpose of this study was to develop a rapid and accurate diagnostic test for palpable breast masses in women under age 40. Methods: Masses were evaluated utilitzing a modified triple test score (MTTS), which assigned scores of I point for benign, 2 points for suspicious, or 3 points for malignant findings from physical examination, ultrasonography, and fine needle aspiration. The MTTS was the sum of the three scores and was correlated with biopsy or follow-up. Results: Among 113 masses, 100 scored 3 points, 8 scored 4 points; all were benign. Three scored 5 points; I was malignant. Two scored greater than or equal to6 points: both were malignant. Conclusions: The MTTS has 100% diagnostic accuracy when other than 5 points. Masses scoring less than or equal to4 points are benign. Masses scoring greater than or equal to6 points may proceed to definitive therapy. Masses scoring 5 points (3%) require biopsy. This approach avoids open biopsy in the majority of cases, while capturing all malignancies. (C) 2002 Excerpta Medica, Inc. All rights reserved.