Most caucasian patients with X-linked ichthyosis (XLI) reportedly display large genomic deletions involving the entire steroid sulphatase (STS) gene and flanking regions. In this study, we investigated the deletion patterns of the STS gene and flanking regions in 12 unrelated Japanese patients with XLI using the polymerase chain reaction method with 10 markers, including the 5' and 3' ends of the STS gene. Eleven of the 12 patients exhibited deletion of this entire gene, whereas the twelfth patient showed no evidence of deletion. In 10 of the 12 patients, the entire region from DXS1139 to DXF22S1 was deleted, the most common deletion pattern observed in caucasian patients, indicating that there are no racial or ethnic differences.