To elucidate iron utilization patterns of Staphylococcus aureus according to the growth, we checked the residual iron concentration and the production of siderophores at the indicated times while culturing S. aureus ATCC 6538 and 25923 strains in brain heart infusion broth. By using streptonigrin susceptibility test and investigating growth curves in three culture media of which iron concentration is 0.2, 20, 45 uM, respectively, we found out that iron metabolism of 6538 strain was more active than that of 25923 strain. In point of tendency of iron consumption, 6538 strain steeply consumed iron just before the onset of stationary phase, but 25923 strain did gradually iron throughout the growth phase. Nevertheless, total amount of iron consumed by each strain during the growth was almost no difference between the strains. CAS diffusion assay in detecting siderophores showed that siderophore production followed iron consumption. These results suggest that the siderophores play significant role in iron utilization in vitro.