The concept of the sentinel node (SN) arises from the consideration that lymphatic dissemination of tumoral cells is produced in an initial nodular focus before affecting the remaining lymphatic regions. Although this concept has been validated in malignant melanoma and breast cancer, its application to other solid tumors, including gastrointestinal neoplasms, remains controversial. SN detection may play an important role in avoiding the systematic performance of highly invasive surgery. This technique provides individual information and can thus modify the surgical procedure or other therapeutic alternatives. Recently, SN determination has been performed through the laparoscopic approach and this technique could become an important component of the minimally invasive treatment of early-stage gastrointestinal tumors. The reason for SN detection varies according to tumoral localization. Thus, in gastric cancer, the main aim is to broaden the indication for minimally invasive surgery in node-negative patients. In contrast, in colorectal cancer, this technique forms part of the search for methods that help to avoid possible under-staging of the patient, with potential repercussions on the adjuvant therapy required.