Vital blue dyes were used to show the feasibility and accuracy of intraoperative lymphatic mapping of the sentinel node (SN) in patients with melanoma, breast cancer, and other solid tumors. Surgeons who have successfully completed an adequate number of cases of intraoperative mapping and sentinel lymph node dissection (SLND) can use blue dye alone to localize the SN. However, radiopharmaceutical agents can facilitate intraoperative mapping; preoperative lymphoscintigraphy can identify the location of the SN, and intraoperative mapping with the gamma probe can provide an auditory signal that complements the visual guide provided by the blue dye. Studies are required to establish more clearly the intralymphatic kinetics of the various radiopharmaceutical agents. An ongoing international Phase III trial in melanoma, the 2 upcoming trials in breast cancer, and similar trials for other solid tumors will further clarify the future role of SLND.