Abstract Background To determine the feasibility and significance of lymphatic mapping and sentinel lymph node biopsy (SLNB) in patients with gastric cancer. Methods From August 1999 to January 2002, 27 gastric cancer patients underwent lymphatic mapping and sentinel lymph node biopsy using isosulfan blue dye. Results The success rate of SLNB was 96.3% (26 of 27). Accuracy, sensitivity, and specificity were 100%. There were no false negatives. In 26 successful cases, 8 patients had positive sentinel lymph nodes and 18 had negative sentinel nodes. Of 8 patients with positive sentinel nodes, 6 had positive sentinel nodes only at N1 lymph node station, 1 only at N2 station, and 1 had positive sentinel nodes at both N1 and N2 stations. Of 18 patients with negative sentinel lymph nodes, 9 patients had sentinel nodes only at N1, 3 only at N2, 5 at both N1 and N2, and 1 at both N1 and N3. There were no cases in which sentinel lymph nodes were the only sites of metastases. Conclusions Sentinel lymph node biopsy using isosulfan blue dye in gastric cancer is a feasible procedure with high sensitivity and accuracy. Sentinel lymph nodes demonstrate the varied lymphatic drainage. If the sentinel nodes at N2 are positive, it will guide surgeons to do a more extended lymph node dissection in early stage gastric cancer.