The rotational relaxation of the GaAs (110) surface is considered. A cluster model is used for simulating the crystal surface, and some quasi atoms are added in order to saturate the dangling bonds in the cluster boundary. The stable relaxation geometry of the GaAs (110) surface is determined by minimizing the total energy of the cluster calculated by the Extended Huckel Method. According to the calculation a value of 18° for the tilted angle of the surface bond is suggested, it is in fairly good agreement with that given by the partial yield photoelectron spectroscopy. The density of states for the cluster is also calculated, it is shown that for this relaxation model there is no empty cation state existing within the band gap.