Abstract Security of resources becomes more important than ever as the upward trend in the prices of mineral and natural resources continues. Phosphorus and manganese are important minerals to many countries. Phosphorus is in global demand, particularly for making fertilizers, and manganese is an indispensable element in industrial and consumer products. However, the raw materials for these two elements are restricted to certain geographical regions and countries. More importantly, they are not produced in South Korea, although domestic use of each is increasing. In this paper the authors examine domestic phosphorus and manganese flows in South Korea, focusing on the iron and steel industries and using statistical data for 2005. The total phosphorus and manganese usage in South Korea are evaluated to be 380 kt-P/year and 303 kt-Mn/year (manganese ore + manganese alloy). Further, the amounts of phosphorus and manganese lost to steelmaking slag are estimated to be 35.7 kt-P/year and 162 kt-Mn/year. These losses correspond to about 10% of the domestic phosphorus consumption and approximately 53% of the manganese added in steelmaking processes as an alloying element or deoxidation agent. The results from these substance flow analyses suggest that a significantly large ripple effect can be expected if recovery of phosphorus and manganese from slag becomes possible. The potential for converting steelmaking slags into new phosphorus and manganese resources is also discussed from the viewpoint of recovery technology.