For　annealed　(001)-oriented　Pb(Mg1/3Nb2/3)O-3-PbTiO3　single　crystals　in　the　vicinity　of　morphotropic　phase　boundary　(MPB),　two　types　of　field　dependence　of　the　dielectric　response　have　been　observed.　These　two　types　of　single　crystals　showed　different　P-E　(polarization　versus　field)　behaviors.　The　phenomena　can　be　explained　by　assemble　configurations　originated　from　random　fields　and　symmetry　adaptation.　The　degree　of　self-organization　of　domains　increases　with　the　increasing　PbTiO3　(PT)　content.　It　was　deduced　that　one　type　of　the　crystals　was　in　monoclinic　composition　region,　and　the　other　was　in　orthorhombic　or　rhombohedral　composition　regions.　The　frequency　dispersion　shoulder　of　dielectric　spectra　for　the　crystals　was　also　discussed.　(c)　2005　Elsevier　B.V.　All　rights　reserved.