The seroprevalence rate of human T-lymphotropic virus (HTLV) among the Korean blood donor population was studied to determine whether screening for HTLV should be implemented. A total of 15,173 serum samples collected from June to July 2006 at five Blood Centers which are located closely to Japan geographically, where the prevalence of HTLV is known to be high, were tested. Serological screening was done by a chemiluminescence method. Samples reactive repeatedly on serological screening were confirmed further by Western blot, line immunoassay, nested polymerase chain reaction and sequencing of proviral DNA. Six samples tested reactive with the serological assay showing a reactive rate of 0.004%. Among the six samples, one sample was confirmed as HTLV-1 positive, giving a confirmed reactive rate of 0.007%. Based on the results of this study, an extended study will be conducted to evaluate whether introduction of HTLV screening is necessary in Korea.