The purpose of the study is to identify the types of morphofunctional changes in the skin and lymph nodes in response to the introduction of tattoo pigment. Material and methods. The experiment was conducted using 20 non-linear male rats, the material for the study was 60 skin patches with tattoo and 45 nearby lymph nodes. Serial sections of the lymph nodes stained with hematoxylin and eosin were subjected to morpho- and cytomorphometry, and the significance of differences was assessed by Student’s t-test (t) and a reliability index (p). Statistically significant differences were considered at p<0.05. Results. It was established that focal accumulation of pigment dye in the skin of rats when administering tattoos was observed mainly in the papillary layer of the dermis. The regional lymph nodes were macroscopically enlarged and black in color. Microscopically determined measurements of the thickening of the lymph node capsule, the expansion of the sinuses, and the accumulation of pigment in the cells of the reticulo-endothelial system and macrophages were made. Morphometry revealed an increase in the cortical-medullary index by 2.53 times as compared with the intact (non-tattooed) group (p<0.05). The number of macrophages was maximum on the 30th day, exceeding that in the intact group by 4.31 times (p<0.05). The number of degeneratively altered cells decreased, and on the 90th day the number of damaged cells was 24.63±4.95 cells/μm2, exceeding that in the group of intact rats by 1.8 times (p<0.05). Conclusion. As a result of a complex and periodic histological, cytological and morphometric study, it has been established that when administering tattoos, pronounced changes take place both in the skin within the tattoo area and in the surrounding lymph nodes. The data from the study indicate the involvement of lymph nodes as organs of the immune system, and the formation of an immune response to the introduction of a tattoo pigment.