The effect of the phase velocity models on the prediction of fluidelastic instability of a cantilever pipe subjected to gas-liquid internal flow is studied. According to the accepted fluidelastic formulation, a two-phase flow correlation is needed to relate phase velocities in order to solve the system equation. In this study, seven reported correlations, including the homogeneous no-slip model, are used to study the effect of phase velocities prediction on fluidelastic instability parameters, specifically, critical mixture-velocity and critical frequency. Comparisons between simulations and previously reported experiments are performed. Results show that the correlation selection plays an important role in critical mixture-velocity predictions. On the other hand, the critical frequency is less sensitive to the correlation.