In order to obtain desired electromagnetic propertieι high initial permeability and good frequency dependance of initial p permeability, the adding effects of sevral seeds were experimented in Mn-Zn ferrite system. As adding seed grams, calcined at sintering temperature, abnormal grains were disappeared clearly but the density and the initial permcability of sintered Mn-Zn ferrite body were decreased. On the contrary, in case of adding seed rains which were calcined below the calcination temperatnre of matrix particle, abnormal grains remained but the initial permeability was increas$xi$d with proper s$xi$ed content. W With proper seed content, the initial permeability was increased by 10-20% but tbe $alpha$ltoff frequency was not changed.