The most common types of fixed offshore wind turbines (OWT) are steel monopiles, jackets, tripods, and gravity-based structures (GBS). For these structures, the fatigue analysis is a governing limit state due to its dynamic behavior when subjected to wind and wave loads. In this article, the effect of different hydrodynamic load models on the damage sustained by a GBS is assessed. The turbine model is based on the DTU (Technical University of Denmark) 10-MW reference wind turbine, and the dynamic analyses are conducted in the SIMA-RIFLEX software, which can perform coupled time-domain aero-hydro-servo-elastic simulations. Due to the large dimension of the GBS, the hydrodynamic model used to calculate the loads must be carefully chosen so as not to make the structure unfeasible. Among the available models, the most widely used for calculating forces in cylindrical structures is the so-called Morison's equation and the one derived from MacCamy-Fuchs theory. Results show that the use of MacCamy-Fuchs theory can lead to a lower damage ratio when compared to the results obtained via the utilization of Morison's equation.