Fanconi anemia (FA) is a genetically heterogeneous chromosomal instability syndrome associated with multiple congenital abnormalities, aplastic anemia, and cancer. We report that a deletion mutation in the FANCG gene (c.637_643delTACCGCC) was present in 82% of FA patients in the black populations of Southern Africa. These patients originated from South Africa, Swaziland, Mozambique, and Malawi. The mutation was found on the same haplotype and was present in 1% of controls from the black South African population. These data indicate that the birth incidence of FA in this population is higher than 1 in 40 000, which is much higher than previously supposed, and suggest that the FANCG deletion is an ancient founder mutation in Bantu-speaking populations of sub-Saharan Africa. Diagnostic screening is now possible by means of a simple DNA test.