In this paper the non-equilibrium dissociation rates behind strong shock waves are studied taking into account state-to-state vibrational distributions. The non-equilibrium populations of vibrational levels of N-2 behind a shock wave are found from the equations of detailed vibration-dissociation kinetics and used for the dissociation rate calculation. A comparison of the results obtained in the state-to-state approximation with the ones based on the quasi-stationary two-temperature and one-temperature vibrational distributions is presented. The importance of the state-to-state approximation in the relaxation zone behind a shock wave is shown. The dissociation rates have been calculated using different models of dissociation (ladder climbing model, Treanor-Marrone model with various parameters). The influence of different models on dissociation rates is discussed.