OBJECTIVE: Cancer has been the first leading cause of death in Korea. During the period of 1993 - 2003, the mortality rate of cancer increased the most among the 10 major causes of death. The aim of the study is to estimate the cost of cancer in Korea during 1999 - 2003. METHODS: We estimate both direct and indirect cost of cancer using a prevalence-based approach. Direct cost estimates include medical expenditures, traffic cost and caregivers' cost. Indirect costs representing the loss of productivity are estimated based on human capital theory. The cost estimates reported here are calculated at 0% discount rate. The major data sources are National Health Insurance Statistical Yearbook, Annual Report on the Cause of Death Statistics, and Survey Report on Wage Structure. We also use other information such as the Korean Statistical Information System. RESULTS: The estimated costs of cancer are as follows: 9.60 billion US PPP$ ($ hereafter) in 1999, $9.60 billion in 2000, $9.62 billion in 2001, $9.01 billion in 2002, and $9.87 billion in 2003. We find that indirect cost accounts for about 80% of total cost during that period, but the proportion has been dropped since 2000; from 84.6% in 2000 to 78.7% in 2003. The proportions of the cost of male and female cancer patients are about 77% and 23% respectively during the period. The cost of three major cancers in 2003 accounts for 53.3% of total cost of cancers: the cost of liver cancer is $2.26 billion (22.9% of total cost of all cancers); $1.67 billion (16.9%) in stomach cancer; and $1.33 billion (13.5%) in bronchial and lung cancer. CONCLUSIONS: The cost of cancer has been steadily increasing from 1999 - 2003 except 2002, while the proportion of indirect costs has gradually decreased since 2000.