Implantation is the first maternal-embryo crosstalk that only occurs during a finite period called the 'implantation window'. HOXA10, a homeobox transcription factor, plays an important regulatory role during this period. However, the target genes of HOXA10 involved in implantation and decidualization have not been identified. Using a chromatin immunoprecipitation screen, we identified the p300/CBP-associated factor (p/CAF) as a direct HOXA10 target gene in vivo. Adenovirus-mediated overexpression and siRNA-specific knockdown of HOXA10 altered p/CAF promoter activity via interaction with the three consecutive TTAT element units in human endometrial cells. These results indicate that p/CAF is a novel HOXA10 target gene, and HOXA10 promotes human endometrial development, at least in part, through the regulation of p/CAF gene.