Rb null embryos exhibit defective fetal liver erythropoiesis. We used microarrays to compare Wt and Rb null fetal livers and to analyse gene expression differences which accompany and may underlie Rb null fetal liver degeneration, erythroid failure, and erythropoietic island dissolution. We used microarrays to compare Wt and Rb null fetal livers and analyse gene expression changes which accompany and may underlie fetal liver. Keywords: retinoblastoma, fetal liver, erythroblast, macrophage, cell death Overall design: Wild type and Rb null embryos were sacrificed at e12.5 and fetal livers were dissected for RNA extraction. Three embryos of each genotype were analysed.