Résumé : Localization of the sentinel lymph node (SLN) in digestive cancers was performed mainly for colorectal primaries and less frequently for oeso-gastric primaries. This technique is feasible in vivo or ex vivo, with a vital dye and/or with a radiolabeled marker. Technically, detection reliability is good, provided a few simple rules are respected. Such intra-operative mapping leads to the localization of unusual lymphatic spread in 5% of the cases and initial resection can be adapted accordingly. ''Sophisticated'' histological analysis of one SLN, considered negative after a standard pathological examination, leads to three types of additional analyses: scrutiny of multiple serial slices whose prognostic significance is unequivocal when positive, and immunohistochemistry or gene amplification (RT-PCR) to search for circulating cancer cells whose prognostic value is currently uncertain. In the future, the localization and analysis of one SLN could supplant the classic examination of all lymph nodes. If the SLN is proven disease free, only very limited and microinvasive resections would be required to treat some digestive cancers with a curative intent.