The aim of the present study was to investigate the initial state of the as-cast structure of alloys of iron with alloying nitrogen, and the state of structure after their cold plastic working. Tests were carried out using micro-ingots of alloys saturated with nitrogen by the levitation metal melting method. First, Fe-N alloys with two different nitrogen contents were smelted as specimens to be used for describing the reference state (standard specimens). Then, micro-ingots of the principal alloy, i.e. Fe-N-V, were produced, which contained 12 wt.% of vanadium at nitrogen pressures of 0.0284, 0.0568, 0.100 and 0.400 MPa, respectively, and at a temperature of 1973 K. The rate of crystallization of liquid metal cast into small copper ingot moulds was determined from the inter-dendritic parameter. Precipitated nitrides were described by the X-ray method, and microhardness was measured. Then, the cold plastic deformation of those micro-ingots was done, and all tests as for the as-cast state were repeated. The metallographic examination of micro-ingots crystallizing under pressure have shown that they have a structure of highly developed dendrites. It has been shown that in the both cases of nitrogenated alloys the crystallization rate increases with increasing nitrogen pressure inside the reaction chamber. At all obtained crystallization rates in the Fe-N-V (12 wt.%) alloy, nitrides precipitate the more intensively the more nitrogen is contained in the alloy. The hardness level of the as-cast state and of the state after cold plastic working depends, in a natural manner, on the composition and structure of the alloy. The maximum cold work hardening was obtained for the Fe-N-V (12 wt.%) alloy smelted at a nitrogen pressure of 0.0284 MPa.