In order to obtain a better understanding of mechanisms governing the microstructural evolution of nickel base superalloys during forging, experimental and numerical studies have been undertaken. For the experimental part, isothermal compression tests were performed at 1100°C for several ratio and strain rates to reproduce microstructural evolution during industrial forging. The resulting microstructures were analysed by Electron Back Scattered Diffraction method and Transmission Electron Microscopy to identify the dynamic recrystallization mechanisms. In parallel, numerical studies has been carried out in which a crystalline plasticity modelling implemented in the finite element code Abaqus® coupled to a recrystallization Cellular Automaton code was used to simulate forging. The first model allows us to obtain the local mechanical fields (strain, stress, crystallographic orientation, dislocation density …) and the second one predicts the dynamic recrystallization.