The gene coding for human p68, a membrane-associated calcium-binding protein, has been assigned to chromosome 5, using a cDNA clone to probe genomic DNA from rodent-human somatic cell hybrids by Southern hybridisation. The gene was localised, by in situ hybridisation, to 5q32-34. The murine gene was assigned to chromosome 11, using a murine cDNA clone to probe genomic DNA from rodent-rodent somatic cell hybrids.