Several genes involved in the determination of Drosophila body segments share a conserved DNA sequence of 183 nucleotides termed the homoeo box. Homologous homoeo box sequences have been detected in the genome of species ranging from insects and anellids to vertebrates, and a number of homoeo box-containing genomic DNA clones have been isolated from Xenopus, mouse and human. We have recently isolated human complementary DNA clones containing homoeo box sequences, representing transcripts from four different genes. We report here the nucleotide sequence of one of these clones (HHO.c10) and show that the corresponding gene is transcribed in human embryos and fetuses at 5-10 weeks post-conception. A major polyadenylated transcript of approximately 2.1 kilobases (kb), as well as RNA species of higher relative molecular mass (Mr), are specifically expressed at a constant level in spinal cord throughout this developmental period.