Objectives: HTLV-I infections are newly recognized disease entity which are common in some tropical and subtropical areas including southwestern district of Japan. Inspite of geographical adjacency and frequent cultural exchanges between Korea and Japan, it has been known that Korea is not an endemic area and HTLV-I associated illnesses are very rare in Korea. Our study was designed to reevaluate the prevalence of anti-HTLV-I antibodies in Korea and its regional distributions. Methods: Sera were obtained from blood donors from various districts of Korea. Anti-HTLV-I anti- bodies were detected using microtiter particle agglutination test kit( Fujirebio Inc. Japan) employing an indirect agglutination technique. Results: The results were as follows 1) Total 9,281 donors were tested and 12 donors were anti-HTLV-I positive(positive rate = 0.13%) 2) Positive rate was 0.11% in male and 0.46% in female, with relative female sex predominence. 3) Frequency of seropositive donors had tendency to increase gradually with age. 4) Relatively high incidence of anti-HTLV-I positive donors were observed in Jonnam(0.15%), Kyung-nam(0.31%), and Chejue(0.80%) which showed increasing incidence as the district got closer to Japan. Conclusion : In conclusion the prevalence rate of anti-HTLV-I seemed to be very low in Korea. But districts close to endemic areas of Japan showed relatively high incidence of anti-HTLV-I positive donors. Surprisingly high incidence of of anti- HTLV-I positive donors were noticed in Chejue warranting further research on HTLV-I associated illnesses and prevention programs.