The gene for human Elk-1, an Ets-related transcription factor, has previously been localized to a region that lies on the short arm of chromosome X and that is involved in specific chromosomal translocations associated with synovial sarcoma and renal adenocarcinomas. We have used fluorescence in situ hybridization and a panel of tumor-derived somatic cell hybrids to refine the localization of Elk-ll in particular with regard to the rearrangements in these tumors. Elk-1 has been assigned to Xp11.2-p11.4. distal to the OATL1 region.