The electric field profile in the drift region of power MOSFET's with lateral structures and deep junctions been found analytically. From the analysis, the best uniform surface doping den-sity and the depth of the drift region in offset-gate power Mosfet's that introduces the minimum seies resistance and sustains a given junction breakdown voltage is derived. Design guidelines for such MOSFET's are proposed. The comparison with computer simulation results bas shown that it is reasonable for some practical structures.