To compare the costs of XELOX (Xeloda + Oxaliplatin) and FOLFOX4 (5-FU + Oxaliplatin + Leucovorin) for adjuvant treatment of stage III colon cancer in a South Korean setting. Based on the equivalence in efficacy of XELOX from NO16968 trial and FOLFOX4 from MOSAIC trial (the 5 yrs disease free survival rates were very similar 66.1% for XELOX and 66.4% for FOLFOX4), a cost-minimization approach was chosen. The model adopts a payers perspective. Efficacy/Safety data and protocol information were acquired from NO16968 for XELOX, and from the MOSAIC trial for FOLFOX4. As no direct comparison of XELOX and FOLFOX4 for this indication is available, we collected several medical resource use data for these two regimens, which were chemotherapy drug doses, adverse events, hospitalization-ambulatory visits, and drug administration methods. The medical costs for FOLFOX4 were acquired from real world claims data (electronic data interchange, EDI); Catholic medical center in Korea. The direct medical costs for XELOX were also estimated by EDI from Catholic medical center with NO16968 trial. Also, health care utilizations were measured. All data analyses were performed using STATA software. The total direct medical costs for XELOX were estimated to be 13,884,894 KRW and for FOLFOX4 14,509,341 KRW per patient for 24weeks of chemotherapy treatment at same body surface area. The drug costs of XELOX were 12,468,748 KRW and of FOLFOX4 10,831,699 KRW. The line costs and drug administration costs were 82,960 KRW for XELOX and, 943,176 KRW for FOLFOX4, respectively. XELOX is more expensive in terms of drug acquisition costs. However, this is more than compensated by cost savings for drug administration, ambulatory encounters, AE medications, costs for central venous lines, and hospitalization. Additional incidence of hospitalization for FOLFOX4 was 2.3 times greater than for XELOX related hospitalization. XELOX offers cost savings of 644,447 KRW (about 585 US $) per patient compared to FOLFOX4 from the payers perspective in South Korean Universal Health Insurance System.