This work is devoted to the study of the mechanical parameters of AISI 316L stainless steel during nano- and microindentation, such as nanohardness (НNI), microhardness (HMI), Young's modulus (E), plasticity indices (H/E) and resistance (H3/E2), relaxation parameters hs, hres, he-p, and their dependence on the magnitude of the load P applied to the indenter. It was shown that in the microindentation interval (P = 100 – 500 mN), the hardness decreases slightly with load increasing, and in the nanoindentation region (P < 100 mN), the hardness increases significantly with P decreasing, demonstrating the Indentation Size Effect. As a result of studying the specifics of the indenter penetration, the main features of the deformation process were established, the participation of various mechanisms of plastic deformation in the indentation of AISI 316L steel (intragranular, intergranular, and rotational) was confirmed, and a physical interpretation of the observed patterns was proposed. The results obtained are of great importance for practice, since AISI 316L steel is one of the medical steels used for implants of various purposes (in dentistry, bone implantology, and biotechnology).