Using homozygosity mapping in a large consanguineous family, we have localised to chromosome 9p a further gene for the autosomal recessive, genetically heterogeneous disease Fanconi anaemia (FA). This is the fourth of at least eight FA genes to be localised to a discrete chromosomal region. Previously localised genes are FAA, FAC and FAD. By analysis of assigned families we show that the gene localised to chromosome 9p is FAF, FAG or FAH, or a new FA gene, and refine the localisation to the 21 cM region between markers D9S1678 and D9S175.