Grinding stage has one of the highest production costs in mining operations due to the intensive use of energy needed for the comminution process. Hence, any improvement in the energy use of this process will have an important impact on production costs. Paper presents the results of an extensive testing program to determine the effect of lifter wear on the power demanded by the grinding mill. Selected power-speed curves covering up to 110% of critical speed are reported. Using these results, a lifter wear factor is proposed to include this effect on the power demand expressions of grinding mills. Results show that for dry grinding, as the lifters wear, the power needed for a specific operating condition increases. Using these results, mill operators will have an important piece of information to set the best operating point for an efficient ore comminution and efficient energy consumption. It will also help to define the appropriate date for a liner change.