We discuss the effects of the directional spreading on the occurrence of extreme wave events. We numerically integrate the envelope equation recently proposed by Trulsen et al., Phys of Fluids 2000, as a weakly nonlinear model for realistic oceanic gravity waves. Initial conditions for numerical simulations are characterized by the spatial JONSWAP power spectrum for several values of the significant wave height, steepness and directional spreading. We show that by increasing the directionality of the initial spectrum the appearance of extreme events is notably reduced.We address the occurrence of extreme wave events in numerical models of random, directional, oceanic sea states. Extreme ocean waves of this type are of unusually large size with respect to the background, surrounding waves. They are often refered to as "freak" or "rogue" waves and have been given a rough definition in terms of an arbitrary threshold, H max > 2.2H s , for H s the significant wave height [1]. Because extreme waves are rare, and hence are not often measured , the physical mechanisms for their occurrence have not been unequivocally established. Possible causes of freak waves in the open sea have been investigated by many researchers [2] and basically three mechanisms have been proposed: the linear interaction of the waves with the currents (geometrical optic theory), see [3][4][5]; the simple linear superposition of Fourier phases (the resulting large waves are also known as transient waves [6]) and the modulation instability [7].The last mechanism and indeed the method addressed herein is based on the nonlinear phenomenon known as the Benjamin-Feir instability [8], which describes how a monochromatic wave train can be unstable to small, side-band perturbations. This physical phenomena has been widely studied in wave tank facilities (see for example [9], [10] and references therein) and from a theoretical and numerical point of view for the 1+1 Nonlinear Schroedinger equation (NLS equation in one space and one time dimensions) [11,12] and for the fully nonlinear Euler equations [13]. A major complication arises from the fact the envelope equations (for example NLS) are derived from the primitive equations of motion under the hypothesis of a narrow-banded spectrum. Higher order equations in the envelope hierarchy have then been proposed [15,16] in order to overcome the limitation of narrow bandwidth. Numerical simulations of these equations in 1+1 dimension [14,17] have shown that the probability of occurrence of freak waves is strictly related to the "enhancement" coefficient γ and the Phillips parameter α of the JONSWAP power spectrum [18]. In [14,17] it was found that increasing the values of γ and α has the effect of increasing the probability of finding freak wave events. In addition to the physical limitations associated with the narrow spectral width assumption, an even more severe limitation of the above results arises because these conclusions have been obtained from essentially one-dimensional numerical simulations.In this co...