It was found that the corrosion rate of Fe-Mn-Si SMA alloys increases with increasing of Mn content: 0.48, 0.59 and 0.80 mm/year for Fe-23 Mn-5 Si, Fe-26 Mn-5 Si and Fe-30 Mn-5 Si alloys, respectively. Such an increase in the corrosion rate may be associated with a change in the phase composition, caused by a higher content of Mn [13]. Among other reasons for the decrease in the corrosion resistance of Fe-based alloys after alloying with Mn, are the high chemical activity of Mn, i.e., low electronegativity, a high negative value of the standard electrode potential, as well as an increased tendency to form non-metallic inclusions [24; 25; 26; 27]. At the same time, it should be noted that a high content of manganese leads to pronounced pitting corrosion in chloride media [28]. Alloying has long been considered an effective method of controlling the corrosion rate of a metal due to its ability to either change the corrosion potential or cause micro-galvanic corrosion. Unfortunately, only a limited number of the alloying elements can cause such an effect. Therefore, other possibilities of manipulating the structure and phase composition are being studied. The concept of changing the phase composition revolves around enhancing galvanic corrosion by creating various phases with different potentials. It has been reported that this approach is also effective for bioresorbable Fe-Mn alloys [23; 29]. However, in this case, there is also a limitation on the phase composition. In order to use magnetic resonance imaging (MRI)during implantation for medical control, the material after deformation must be in an antiferromagnetic state (austenite, \(\varepsilon\)-martensite). An important role in increasing the corrosion rate is played by structural defects that occur during metal processing. Violations of the regularity of the crystalline structure have a higher free energy and can become a place for the initiation of corrosion in crystalline materials [30; 31]. Dislocations and grain boundaries can serve as preferred sites for the nucleation of nonequilibrium intermetallic phases [32], which can subsequently form galvanic cells with a metal matrix. In addition, it is known that the grain size affects the corrosion characteristics of the alloy. A model [33] was proposed that describes the relationship between the corrosion current density and the grain size of pure metals. Within this model for corrosion in a physiological environment, grain refinement can lead to an increase in the corrosion current density. At the same time, grain refinement leads to an increase in the density of grain boundaries. Their effect on the corrosion resistance of the alloy depends on the angles of their misorientation [34] and on the type of boundaries. Thus, in Fe-based alloys, low-angle grain boundaries lead to a decrease in susceptibility to intergranular corrosion, in contrast to high-angle grain boundaries [35]. Twins in the austenitic structure of these alloys have low energy special boundary, which increase the corrosion resistance in contrast to high-energy twin boundaries of the Mg alloys [36]. The current state of research shows great scientific interest in the direction of studying the processes of degradation and increasing the corrosion rate of alloys with SMA, including Fe-Mn-Si alloys. However, significant progress in solving the problem of increasing the rate of degradation has not yet been achieved. In this work, an attempt was made to increase the rate of degradation of the Fe-Mn-5 Si alloy by refining the structure by the method of equal-channel angular pressing (ECAP), while maintaining the austenitic state. The article presents a comparative analysis of the corrosion rate of the alloy measured by various methods. Studies of the biocompatibility and degradation of Fe-Mn-Si alloys in vitro are supplemented by in vivo results, which are currently limited [19; 20].