Recent studies have suggested that at least three transcription-initiation sites were present in the human H-type alpha(1,2)fucosyltransferase gene (FUT1). In the present study, we have investigated these transcription start sites of FUT1 in undifferentiated leukemic cells (K562) that have erythroid characteristics, in erythroleukemia cells (HEL), and in bone marrow cells. K562 cells used exclusively exon 1 as the start site. While HEL cells used mainly exon 2 as the start site, the major start site for bone marrow cells was within exon 7. In addition, we investigated the transcription start site(s) in vascular endothelial cells (ECV304) as an example of mature cells and found that the start site was predominantly within exon 7. The promoter activities were found in the 5' flanking regions of these three start sites after transfection of constructs with luciferase reporter gene into K562 and HEL cells. These findings suggested that the transcription start sites of FUT1 changed during differentiation of the erythroid lineage and that the tissue-specific and stage-specific expressions of the FUT1 were regulated by three distinct promoters. We also found that the 5' flanking region of exon 2 (intron 1) consisted of repetitive sequences (chromosome 19-specific 37-bp minisatellite repeats, Alu sequence and long terminal repeat) and that the start site of exon 2 was within the long terminal repeat. Thus, these repetitive sequences may play a role in the expression of the FUT1.