The sentinel node concept has been widely discussed, and the technique of sentinel navigation surgery has been advocated. However, in the oral environment, the study of the lymphatic architecture has been hampered by the presence of hard tissues such as teeth and bone. In this study, we examined the distribution of lymphatic vessels in the gingiva using an enzyme-histochemical method, 5'-nucleotidase staining. In the buccal free gingiva, the density of lymphatic vessels was 7.8±0.4 on the oral epithelium side and 4.8±2.4 on the sulcal epithelium side. In the lingual free gingiva, the density was 9.4±0.3 on the oral epithelium side and 3.3±0.2 on the sulcal epithelium side. As a result, we concluded that the lymphatic network within the sulcal epithelium intrinsically provides a much poorer flow than the lymphatic network of the oral epithelium, similar to the blood capillary network. [MVRC 2(1):