In this original work, the dislocation structure and NbC precipitation were investigated in three Ni-based alloys (70Ni-Fe-0.331Nb-0.040C, 70Ni-Fe-0.851Nb-0.114C and 70Ni-Fe-1.420Nb-0.157C, wt%) thermomechanically processed in the temperature range of 1250-1075 °C. The dislocation structure inhomogeneity (dislocation networks and cell walls), which we observed in the middle and high Nb+C alloys, resulted from the dislocation pile-ups in the vicinity of >200 nm NbC particles. The dislocation density around >200 nm particles exceeded the average values by 5-7 times, and that in the cell walls might exceed the average values by 10 times. Twins and stacking faults were observed in all alloys after solution treatment at 1250 °C, however, they were not observed after 1.2 strain at 1075 °C. The dislocation generation rate during deformation at 1075 °C varied with alloy composition and increased with an increase in the°C, the majority of particles were growing in the high Nb+C alloy, theNb+C alloy and all the particles were dissolving in the low Nb+C alloy. Deformation to 1.2 strain at 1075 °C resulted in strain-induced precipitation in all alloys andNb+C alloys.