Palpable breast masses may become evident during breast self-examination or clinical breast examination or retrospectively after screening mammography. Because most breast masses do not exhibit distinctive physical findings, imaging evaluation is almost always necessary to characterize the lesions and screen the reminder of both breasts. Depending on age, the primary imaging evaluation of a palpable breast mass is mammography or breast ultrasound. Negative imaging results should not deter the biopsy of a clinically suspicious breast mass.