Optimum working life of tractor and farm machinery employed in potato production in Hamadan Province was assessed through Data Envelopment Analysis. An input oriented model was applied to determine the optimized machinery system. In this model inputs were the lifetime of tractor as well as seven involved machines including moldboard plow, potato planter, chemical fertilizer spreader, tractor mounted sprayer, furrower, potato haulm cutter and potato digger, while outputs were: yield (kg ha-1), economic return (kg thousand Rials-1) and energy (kg MJ-1) as productivity indices of potato cultivation. Results revealed that 38% of farms were inefficient. They, due to old machinery, cannot be economically efficient and are spending extra energy. On the other side, efficient farms, through an employment of optimized new machinery pay less maintenance cost and can produce more economically with a less energy spending. Also, analysis showed that the utmost mechanization employed on the farms is the use of tractor and moldboard plow. If inefficient farms use suitable mechanization systems, they can raise to even a duplicate level, their economic return by raising their energy productivity (up to 70%) and improving the yield.