THE homeobox is a 183-base-pair DNA sequence originally found in Drosophila segmentation and homeotic genes^1,2. In Drosophila, homeotic genes are clustered in the Antennapedia and Bithorax complexes, collectively called the homeotic gene complex (HOM-C)³. In the mouse genome, about 40 homeobox genes (Hox) are clustered in four chromosomal regions (Hox A to D). The Hox genes are arranged in the same order and have the same antero-posterior pattern of expression as their structural homologue in the HOM-C^4,5, suggesting that they control mouse pattern formation in the same way that HOM-C members do in Drosophila. Homeobox gene products are believed to be transcription factors that regulate expression of target genes. A few candidate target genes have been identified in Drosophila by various approaches⁶ but the Hox gene targets are poorly understood, mostly because of limitations in the available approaches. Here we identify several candidate Hox gene targets, including a mouse homologue of the Drosophila tumour-suppressor gene l(2)gl, by immunopurification of DNA sequences bound to a Hox protein in native chromatin.