Assessment sentinel node coloration by the patent blue dye technique during breast carcinoma surgery largely depends upon the surgeon. It would therefore be valuable to define a procedure to validate the quality of the surgical specimen. With this aim, we have analyzed a series of 141 cases of sentinel nodes and determined whether the blue color of the node persisted after formalin fixation and could be assessed by examination of the tissue blocks. The pathologist's macroscopic control confirmed blue coloring in 114/141 cases (81%). This rate was similar when the sentinel node was metastatic (82.5%) (40 cases) or non metastatic (81%) (101 cases). Checking the color of the lymph node is a simple method to verify the quality of the surgical specimen. This item should be included in the pathologist's report. Several mechanisms can account for the lack of coloring of true sentinel nodes.