Accidental switching of tissue specimens in the histology laboratory can result in significant medical error. We sought to evaluate inking breast core needle specimens as a method to reduce the chance of specimen mix-up. We sequentially inked 1,000 consecutive breast core specimens with 6 different colors. Review of the color of the ink revealed 3 discrepancies: 1 related to blocks being switched, 1 related to incorrect labeling, and 1 was a typographical error. Inking of breast core specimens is a simple, inexpensive, and effective way to help reduce the chance of specimen mix-up.