The ambient turbulence intensity is a key factor in the study of marine current turbines. Indeed recent studies have shown that ambient turbulence intensity highly modifies the behavior of horizontal axis marine current turbines. Consequently numerical simulations have to represent the ambient turbulence or at least its effects on the performance and wake of the turbines. This paper presents the latest numerical developments carried out at LOMC in collaboration with IFREMER in order to take into account the effects of ambient turbulence.