A life-cycle inventory (LCI) of steel based on exergy values is presented. Exergy accounting of energy and materials flows for distinct steel production processes - conventional integrated, semi-integrated and new integrated with smelt reduction - is used to calculate and compare exergy losses and efficiencies for each case. The exergy LCI provides an integrated measure of resources, products and wastes at different aggregation levels, from single unit operations and upstream production steps to steel plants and production routes. Exergy values for pollution and wastes are presented and discussed. A sensitivity analysis is performed in order to test how variations in some parameters affect the results of the total exergy accounting for the different steel production routes.