A homeobox is a DNA sequence of 180 base pairs that encodes a DNA-binding domain known as a homeodomain. The polymerase chain reaction (PCR) has been used to prepare probes of homeobox-containing genes. We cloned and sequenced the amplified products of PCR that was performed with human genomic DNA and two primers that correspond to well-conserved regions in homeoboxes. Fifteen kinds of homeobox gene were identified and 13 of them were assigned to HOX genes that have already been reported. Two others represented novel homeobox genes and one of them, GBX1, was mapped to chromosome 7q36.1 by fluorescence in situ hybridization. Northern hybridization of mRNA for various kinds of hematopoietic cell showed that the newly identified GBX1 gene is expressed in K562 cells and Daudi cells.