The　(1　-　x)BaTiO3-x(Bi3/4Na1/4)(Mg1/4Ti3/4)O-3　(0.2　a　parts　per　thousand　currency　sign　x　a　parts　per　thousand　currency　sign　0.9)　ceramics　were　prepared　by　conventional　solid-state　reaction　route.　Their　dielectric　properties　were　found　to　follow　a　modified　Curie-Weiss　law　and　an　empirical　Lorenz-type　relation　in　respective　temperature　regions.　Their　dielectric　relaxation　times　fit　well　with　the　Vogel-Fulcher　relation　for　x　=　0.2,　0.3,　and　0.4.　For　x　=　0.5,　0.6,　0.7,　and　0.8,　however,　the　fitting　curves　of　Vogel-Fulcher　relation　showed　certain　deviation　from　the　experimental　data.　Based　on　the　theoretical　treatment　of　Landau-Ginsburg-Devonshire　theory,　an　approximate　treatment　of　the　E-field　dependence　of　the　permittivity　was　adopted　and　found　to　describe　well　the　field　dependence　of　the　permittivity　for　x　=　0.3　at　temperatures　equal　to　and　below　T　(m)　(temperature　of　maximum　dielectric　permittivity).　A　combined　Langevin-type　expression　used　in　the　present　work　appears　to　give　a　good　account　for　the　field　dependence　of　the　permittivity,　assuming　polar　regions　are　of　a　statistical　cluster　size.　For　polar　clusters　of　linear　dimension　L　similar　to　4-8　nm　for　instance,　the　fitted　values　of　polarization　are　in　the　range　of　P　similar　to　6.2-9.8　mu　C/cm(2).