Real high energy laser systems are rife with sources of phase (and amplitude) distortions that usually tend to degrade the far field irradiance distribution. Recent advances in deformable mirror design, beam sampling devices and concept implementation technology may make it possible to perform on line phase compensation. However, there are limits to the performance capabilities which are mostly a result of the spatial and/or temporal characteristics of the phase aberrations. Nonetheless, it might be possible to significantly improve the performance of high power laser systems by utilizing the adaptive optics technology that is available today. This paper will address some of that technology.