The effect of TiO$_2$addition has been studied on the power loss, density, initial permeability, resistivity, and microstructure of Mn-Zn ferrites. TiO$_2$addition increased the density of sintered body and decreased of the initial permeability. Activation energy for electron hopping as well as electrical resistivity increased with TiO$_2$addition. The toroidal core sintered at 1150 $^{circ}C$ with 1.5 wt% of TiO$_2$demonstrated the power loss of 83 mW/㎤ at 1 MHz, 25 mT, 8$0^{circ}C$. However, the same specimen sintered at 120$0^{circ}C$ lead to the power loss, 1168 mW/㎤ at 1 MHz, 25 mT, 8$0^{circ}C$ and developed an exaggerated grain growth.