The effect of heating and weak pulsed magnetic field on microplastic deformation of high-nitrogen steels is studied. The methods of optic metallography, X-ray analysis, microhardness measurement and internal friction were used. As a result of experimental investigations it is stated that in high-nitrogen Cr - Mn steel at heating (low-temperature range) structure transformations take place. It is shown that at heating from 20 to 300 °C the processes of interaction between nitrogen atoms and extended dislocations take place. Kinetics of processes is similar to kinetics of ageing, but with certain variations. The obtained strucrure is unstable and trends to recovery of the initial state during 10 - 100 h. The influence of TPMF has similar nature. Presumably this process is determined by the redistribution of nitrogen in solid solution-nitrogen phases-dislocation atmospheres system. The authors propose to apply heating up to 400 °C during 4 - 8 h in order to stabilize the dislocation structure.