We have localised the human cDNA for neurone-specific enolase (ENO2) to chromosome region 12p13 by in situ hybridisation. Two additional smaller peaks of hybridisation to specific chromosomal subregions were observed. That on chromosome 1p36 probably represents cross-hybridisation to the locus for nonneuronal enolase (ENO1), which has been previously localised to this chromosome and with which ENO2 shares homology. A further gene for a member of the enolase family may be responsible for the hybridisation to chromosome 17.